Chemical Reactions & Equations - Saraswati Chemistry · Web viewHow are mineral transport in plant...

SARASWATI STUDY POINTChemical Reactions & Equations

1. What change do you observe, when magnesium ribbon is burnt in air?

2. Define the term word equation.

3. What is meant by thermal decomposition?

4. What is an example of decomposition reaction?

5. Name the term used for the physical state of the solution of the reactant or product dissolved in water.

6. Name the chemical reaction in which heat is absorbed.

7. Give reason- Magnesium ribbon is to be cleaned before burning in air.

8. Define Corrosion and Rancidity. What is Redox reaction?

9. Name the gas which burns with a pop sound.

10. Name one metal which does not corrode.

11. Name the type of reaction in which two or more substances combine to form a new single product. What happens when current is passed through water?

12. What change do you observe on the surface of copper when its powder is heated?

13. Give one disadvantage of oxidation in our daily life.

14. Name the group of chemical substances used to prevent oxidation.

15. Why state food has a peculiar smell?

16. Which type of chemical reaction takes place when Barium hydroxide and Ammonium chloride are mixed together in terms of heat released or absorbed?

17. Name the type of reaction taking place when iron nails are dipped in copper sulphate solution. Write one disadvantage of corrosion of metals.

18. What happens when calcium oxide reacted with water? Write the chemical equation of reaction involved. What is balanced chemical equation? Why a skeletal equation should is to be balanced?

19. Write the four changes which help us to determine whether a chemical reaction has taken place. Write the balanced equation for silver bromide kept in sunlight?

20. What information regarding physical state do you get from the following notations:- (g), (l), (aq) and (s) ?

21. Arrange iron, zinc and copper in increasing order of reactivity from the following reaction:- Fe + CuSO4 → FeSO4 + Cu, Zn + FeSO4 → ZnSO4 + Fe

22. Explain Oxidation and Reduction in terms of gain or loss of oxygen, giving eg.s.

23. Respiration is considered an exothermic reaction. Explain why?

PITAM PURA & ROHINI (www.saraswatichemistrypoint.com) 011-27316087 / 9899899326 1

SARASWATI STUDY POINT24. Write two methods by which oxidation process of food can be slowed down at home?

25. When lead nitrate powder is heated which odour fumes are evolved? Also name the gas evolved.

26. What happens when sodium sulphate solution is added to barium chloride solution? Give the chemical equation of the reaction.

27. Oil and fat containing food items (chips) are flushed with Nitrogen. Give reason.

28. What happens when a strip of zinc is dipped into a solution of copper sulphate? Write the balanced chemical equation of the reaction?

29. Define decomposition reaction. Give one example each of thermal decomposition and electrolytic decomposition.

30. Translate the given statement, first in word equation and then into skeleted equation:- Solutions of Barium chloride and sodium sulphate in water reacts to give insoluble barium sulphate and the solution of sodium chloride.

31. Write the balanced chemical equation for the following reactions:-(i) Barium chloride + potassium → Barium sulphate + Potassium chloride.(ii) Sodium chloride + Silver nitrate → Silver chloride + Sodium nitrate(iii) Calcium hydroxide + Carbon dioxide → Calcium carbonate + water.

32. Name the type of chemical reaction represented by the following equations:-(i) CaCO3 (s) Heat CaO (s) + CO2 (g)(ii) CaO (s) + H2O (l) → Ca(OH2) (aq)(iii) Zn (s) + CuSO4 (aq) → ZnSO4 (aq) + Cu (s)

33. Define displacement reaction. Give one example of it. How is it different from double displacement reaction?

34. Translate the following statements into chemical equations and balance them:-(i) Sodium chloride reacts with silver nitrate to give sodium nitrate and a precipitate of silver

chloride.(ii) Hydrogen gas combines with nitrogen to form ammonia.(iii) Zinc carbonate decomposes to give Zinc oxide and carbon dioxide.(iv) Ammonia gas reacts with water to give ammonium hydroxide.(v) Copper (II) oxide on heating with hydrogen gas gives copper and water.

35. Identify the substances that are oxidized and the substances that are reduced in the following reactions:-

(i) ZnO + C → Zn + Co(ii) CuO + H2 → Cu + H2O(iii) MnO2 + 4HCl → MnCl2 + 2H2O + Cl2

36. Balance the following equations and state whether they are exothermic or endothermic: -(i) Na + H2O → NaOH + H2 + Heat(ii) FeSO4 (s) → Fe2O3(s) + SO2(g) + SO3(g)(iii) CaCO3 (s) → CaO + CO2(g)PITAM PURA & ROHINI (www.saraswatichemistrypoint.com) 011-27316087 / 9899899326 2

SARASWATI STUDY POINT

37. Name the type of chemical reactions taking place when:-(i) Lime stone is heated.(ii) Magnesium ribbon is burnt in air.(iii) Burning of coal(iv) Iron nails are dipped in copper sulphate solution.(v) Sodium sulphate is is mixed with barium chloride.

38. For the following equation:- Pb (NO3)2 (s) → PbO (s) + NO2 (g) + O2(g)(i) Write the name and colour of the precipitate formed.(ii) Balance the above chemical equation.(iii) Name the type of chemical reaction.

39. Translate the following statements into balanced chemical equations:-(i) Sodium chloride reacts with silver nitrate to give sodium nitrate and a precipitate of silver

chloride.(ii) Hydrogen gas combines with nitrogen to form ammonia(iii) Zinc carbonate decomposes to give zinc(iv) Ammonia gas reacts with water to give ammonium hydroxide.(v) Copper oxide on heating with hydrogen gas gives copper and water.


SARASWATI STUDY POINTAcid, Base & Salts

1. Define dilution.

2. Name the acid produced by our stomach?

3. Name two olfactory indicators.

4. Name two natural indicators.

5. What change in color do you observe when turmeric mixes with a base.

6. Define neutralization reaction.

7. What are alkalis?

8. How can the pain and irritation caused by the stung of honey bee relieved?

9. Give reason: Acids conduct electricity only in presence of water.

10. Write is tartaric acid added to baking soda in baking powder.

11. What is Brine?

12. Name two synthetic indicators.

13. Name the acid present in nettle leaves.

14. What change in colour do you observe when methyl orange is mixed with an acid?

15. Name the group of substances used to neutralize the excess acid in our stomach.

16. What are those indicators called whose odour changes in acidic or basic media?

17. Name the gas evolved when an acid reacts with a metal?

18. Why Bee- sting causes pain and irritation?

19. Why curd and sour substances should not be kept in brass or copper vessels?

20. Name the components present in baking powder.

21. What is the pH of acid rain?

22. Name the gas evolved when sodium hydroxide reacts with zinc.

23. While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid?

24. Write the chemical name of plaster of Paris.

25. Name the chemical compound which was the important symbol in India’s struggle for freedom.

26. What happens when the blue crystals of copper sulphate are heated?PITAM PURA & ROHINI (www.saraswatichemistrypoint.com) 011-27316087 / 9899899326 4

SARASWATI STUDY POINT27. How is the concentration of hydronium ion (H3O+) affected when a solution of acid is diluted?

28. Three solution X, Y and Z have pH values 8,9 and 10 respectively, arrange them in increasing order of their basic character.

29. Fresh milk has a pH of 6. Write the change in pH when it turns into curd.

30. Why is the process of producing sodium hydroxide called chlor-alkali process?

31. What will happen when sodium hydrogen carbonate is heated? Write the chemical equation of the reaction involved.

32. A milkman added a small amount of baking soda to fresh milk.

33. Write differences between acidic and basic salts.

34. A baker found that the cake prepared by him is hard and small in size. Which ingredient has he forgotten to add that would have made the cake fluffy? Give reason.

35. Why does distilled water not conduct electricity, whereas rain water.

36. Why plaster of Paris should be stored in a moisture proof container. Write a chemical equation of the reaction between plaster of Paris and water.

37. Write the pH of the following:-(i) Gastric juice(ii) Blood(iii) Lemon juice(iv) Milk of magnesia

38. What is the effect of acid and base on phenolphthalein, whereas rain water does?

39. Four test tubes A, B, C and D contain the solution having pH 3, 5, 8 and 12 respectively. Arrange them in increasing order of acidic character. Give reason in support of your answer.

40. Define water of crystallization. Write the number of water molecules present in one formula unit of copper sulphate crystal.

41. A metal compound X reacts with dilute Hydrochloric acid to produce effervescence. The gas evolved extinguishes a burning candle and turns lime water milky. Identify the gas evolved. Write a balanced chemical equation for the reaction if one of the compounds formed is CaCl2.

42. What happens when metal carbonates and metal hydrogen carbonates react with acids? Write the word equations in each case.

43. Under what soil condition do you think a farmer would treat the soil of his field with quick lime (CaO) or slaked lime [Ca (OH)2]. What should be the nature of soil for a healthy growth of plants?


SARASWATI STUDY POINT44. Give reason-HCl, HNO3 etc., show acidic characters in aqueous solutions while alcohol and

glucose solutions do not show acidic character.

45. Name the gas liberated when an acid reacts with a metal. Illustrate with an example. How will you test the presence of this gas?

46. Name the acid present in following natural sources:-(i) Vinegar(ii) Tomato (iii) Tamarid

47. On passing excess carbon dioxide gas through lime water, if first turns milky and then becomes colourless. Explain why? Write the chemical reactions taking place.

48. Illustrate with an activity that compound like Alcohol and Glucose contain hydrogen but are not categorized as acids.

49. Draw a flow chart showing uses of products from chlor-alkali process.

50. You are provided with three test tubes A, B and C. A contains distilled water, B and C contains acidic and basic solutions respectively. If you are given only blue litmus paper, how will you identify the nature of solution in three tubes?

51. Name the raw materials used in manufacture of Baking soda. Write two important uses of Baking soda.

52. Name the hardest chemical substances in the body of which tooth enamel is made. At what pH in the mouth it gets corroded? What kind of toothpaste should we use to protect our teeth?

53. A sanitary worker uses a white chemical having strong smell of chlorine gas to disinfect the water tank. Identify the chemical compound. Write its chemical formula. Give the chemical equation for its preparation.

54. What is Chlor-alkali process? Write the chemical reaction taking place in form of chemical equation. Name the gases given off at the anode and the cathode respectively. Write one use each of any two products produced in this process.

55. Five test tubes A, B, C, D and E contain solutions having pH 2, 4, 14, 7 and 8 respectively. Among these solutions which one is:-

(i) Strongly acidic (ii) Strongly basic (iii) Neutral(iv) Weekly acidic (v) Weekly basic

Arrange the pH in decreasing order of hydrogen ion concentration.


SARASWATI STUDY POINT56. What happens when

(i) Excess of carbon dioxide is passed through lime water(ii) Dry chlorine gas is passed over slaked lime(iii) Electricity is passed through an aqueous solution of sodium chloride (iv) Gypsum is heated at 373k(v) A solution of sodium hydrogen carbonate is heated

57. Out of sodium hydrogen carbonate, sodium carbonate, plaster of Paris, bleaching powder, sodium hydroxide

(i) Name the compound used for selling fractured bones.(ii) Name the compound used for making baking powder.(iii) Name the compound used for softening hard water.(iv) Name the compound used for bleaching cotton in textile industry.(v) Name the compound used for making soaps and detergents.

Also write their chemical formula.


SARASWATI STUDY POINTMetals & Non-metals

1. Name two metals which have very low melting points and melts if you keep them on the palm.2. Name the non-metals which are lustrous.3. Name two most malleable metals.4. Define ductility. Name the most ductile metal.5. Name two metals which are best conductors of heat.6. Name two metals which start floating in water.7. Name one metal and one non-metal which exist in liquid state at room temperature.8. Name two metals which can be cut easily with knife.9. What is the nature of oxides formed by metals and non-metals?10. Name two metals which do not react with water but react with steam?11. What is the colour of flame when magnesium burns in air?12. What type of chemical bond is present in sodium chloride?13. Name the allotrope of carbon which is the hardest natural substance known and has a high

melting point.

14. Why sodium and potassium metals are kept in kerosene?

15. Name two metals other than silver and gold, which do not react with water even in form of steam.

16. Name the reducing agent in the following chemical reaction:- Fe2O3 + Al → Al2O3 + Fe

17. Which two metals liberate hydrogen gas when reacts with dilute Nitric acid?

18. Select a most reactive and a least reactive metal from the following: Al, Ca, Zn, Fe, Hg, Cu.

19. What is an amalgam?

20. Name one cheap reducing agent commonly used in extraction of purity metals.

21. Name the electrolyte used in electrolytic refining of copper.

22. Name the process by which metals which is at the top of activity series are extracted from their ore.

23. In electrolytic refining, name the electrode which is made up of impure metals and the electrode which is made up of pure metals.

24. Why Aluminium cannot be obtained by the reduction of its ore with carbon?


SARASWATI STUDY POINT25. What name can be given to the insoluble impurities which settle down at the bottom of the

anode during electrolytic refining of metals?

26. Name the metal which does not react with dilute Hydrochloric acid.

27. An element ‘A’ reacts with oxygen to form an oxide which dissolves in water to give an aqueous solution which turns red litmus blue. Element A is metal or non metal.

28. Differentiate between Roasting and Calcination. Give one example of each.

29. Is hydrogen gas evolved when most metal reacts with nitric acid? Why?

30. A metal M left in moist air for a longer time loses its shiny brown surface and gains a great coat. What is this green coloured compound and identify the metals.

31. Why sodium chloride has high melting point?

32. What are amphoteric oxides? Give two examples of such oxides.

33. Explain why magnesium metal after reacting with hot water starts floating on its surface. Write the chemical equation of the reaction.

34. Give two differences between metal and non-metal on the basis of their chemical properties.

35. Give reason- Ionic compounds conduct electricity only in molten state not in solid state.

36. An alloy is used electronic industry to wield the components. Name the alloy and its constituents.

37. Define reactivity series of metals. Rearrange the following metals in increasing order of their reactivity: Zn, Al, Fe, Cu, Au, and Ca.

38. Illustrate the formation of bonds in:-(i)Sodium Chloride (ii) Magnesium Chloride

39. Write balanced chemical equation for the reaction taking place when:- (i) Zinc carbonate is calcinated. (ii) Cinnabar is heated in air.(iii) Manganese dioxide is heated with aluminium powder.

40. Explain why aluminium is more reactive than iron, yet its corrosion is less than iron.

41. Give reason:- (i) Ionic compounds are solids.(ii) Gold and silver are found in Free State in nature.(iii) Ionic compounds have high melting points.

42. An element A has atomic number 11 and another element B has atomic number 8. A and B combine to form an ionic compound. What would be the formula of the compound formed? Illustrate the formation of compound showing electron transfer.


SARASWATI STUDY POINT43. Write the constituents of the following alloys:-

(i) Stainless steel(ii) Brass(iii) Bronze

44. Name the ore of Mercury. Name the method by which metals like mercury, which is low in the reactivity series can be extracted from its ore. Write the chemical reaction involved in extraction of mercury from its ore.

45. What is meant by refining of metals? Name one method widely used for refining of metals. How this method is different from electrolyte reduction?

46. Write the chemical equations for the following reactions:-(i) Iron reacts with steam(ii) Calcium reacts with water.(iii) Copper is heated in air.

47. What is the reduction between Iron oxide and aluminium known as?Write the chemical equation? Write one use of this reaction?

48. Write the systematic steps involved in the process of Extraction of metal of medium reactivity from its sulphide ore.

49. What are ionic compounds? State four properties of ionic compounds will respect of their physical nature, melting and boiling points, solubility and conduction of electricity.

50. What is meant by rusting? Write an activity to find out the necessary conditions under which iron rusts. Mention two methods used for preventing rusting of iron.

51. A metal E is stored under kerosene. When a small piece of this metal is left open in the air, it starts warming up and the product formed is dissolved in water which turns the red litmus blue:-

(i) Name the metal E.(ii) Write the chemical equation for the reaction when it is exposed to air and when

the product is dissolved in water.(iii) Explain the process by which the metal is obtained from its molten chloride.

52. A metal M which is one of the best conductors of heat and electricity is used in making electric wires is found in nature as sulphides are M2S.

(i) Name the metal M.(ii) Which process will be suitable for the extraction of this metal from its ore M2S?Draw a labelled diagram of electrolytic refining of the metal


SARASWATI STUDY POINTLife Processes

Important terms and definitions:-

Nutrition: - It is a process of intake as well as utilization of nutrients by an organism or intake of food by organisms to release energy for carrying out all life processes.

Nutrient: - It is a substance, which an organism get from its surroundings and uses it either as an energy source or for biosynthesis of body constituents.

Need for Nutrition: - Living organisms continuously require energy for their life processes even during their sleep. (i) Autotrophs (auto-self):- Make their own food using organic raw materials i.e., carbon dioxide and water utilising solar-energy.E.g., all green plants and some bacteria.

(ii) Heterotrophs (hetro-different or other):- Obtain food from green plants either directly or indirectly or “organisms who derive energy from the intake and digestion of the organic substances normally of plants or of animal source”, E.g., all animals, bacteria and fungi.

Types of Heterotrophic Nutrition:-

(a) Saprophytic (Sapro = rotten)

(b) Parasitic (Para = other)

(c) Holozoic

(i) Organisms obtain food from dead and decaying organic matter.

(i) They obtain food from the body of host.

(i) They feed on complex organic matter by ingestion which is digested later.

(ii) Examples:- Fungi and Bacteria.

(ii) Examples:- Cuscuta, Tapeworm, Plasmodium, etc.

(ii) Examples:- Amoeba, Frog, Human beings, etc.

Nutrition in PlantsGreen plants are autotrophs. They synthesize food by the process of Photosynthesis.Site of Photosynthesis is present in upper epidermic in ‘PALISADE’.Size: - 4-6 micrometer in diameter.

In the chloroplast of higher plants, stacks of lamellar structure called grana (singular granum) are present. Its inner membrane lines the lumen of the chloroplast and it is called matrix or stroma. In the cross-section of the grana, lamellae form sac like structures called thylakoids. A thylakoid of one granum is connected to other granum with the help of membrane. It is called stroma lamellae.Main types of chlorophyll are chlorophyll a, b, c, d, e and bacteriophyll.

1. Raw materials – CO2 & H2O2. Site – Chloroplast3. Light absorbing pigment – Chlorophyll4. Over reaction – 6CO2 + 12H2O Sunlight C6H12O6 + 6H2O + 6O2

Chlorophyll


SARASWATI STUDY POINTNutrition in Animals

1. Nutrition in Amoeba:-(i) Ingestion Phagocytosis – Forms Pseudopodia. Engulfs food.(ii) Digestion – Digests food inside food vacuole by enzymes of lysosome.(iii) Absorption – Digested food diffuses into cytoplasm.(iv) Assimilation – Digested food is used by the cell.(v) Egestion – Undigested food is thrown out by the body.

Human Digestive SystemThe organs which are responsible for ingestion, digestion, absorption, assimilation and Egestion constitute the digestive system. The digestive system comprises of the alimentary canal and associated digestive glands. Mouth- It leads into Buccal cavity. The floor of the Buccal cavity has a tongue bearing taste

buds. Man possesses teeth on both the jaws. There are 32 teeth of four different types, namely incisors, canines, premolars and molars.

Tongue- Mixes food with Saliva. Salivary Glands- Salivary glands secrete saliva which contains enzyme ptyalin. It digests

starch into maltose. Oesophagus- Passage of food. Stomach- It is a J-shaped organ which secretes gastric juice containing Pepsin, lipuse, HCl and

mucus. Pepsin digests proteins and lipase digests fats partially. HCl kills germs and mucus protects the wall of stomach.

Duodenum- It is a U-shaped part which receives bile juice from liver. Receives pancreatic juice from pancreas. Bile juice emulsifies fats and pancreatic juice digests carbohydrates, proteins and fats.

Jejunum & Ileum- Intestinal juice called succus entericus completes digestion. Colon- Absorbs water from the undigested food. Rectum & Anus- Removal of undigested food from the body.

End products of digestion in man:-Carbohydrates GlucoseProteins Amino acidsFats Fatty acids & glycerolAssimilation:- Utilization of digested food for

Building new body parts.Repair damaged & worn-out parts.Obtain energy for all life processes.


SARASWATI STUDY POINTDigestion of Food

Organ Juice/Gland Enzyme Function1. Mouth Salivary gland Ptyalin Digest starch to maltose.2. Stomach Gastric juice Lipase, Pepsin Breaks down lipids. Digests proteins to peptones.3.Duodenum(small intestine)

Liver – BilePancreas – Pancreatic juice contains three enzymes

Bile

1. Trypsin2.Amylase3. Lipase

Emulsifies fats (Breaking fats into small glopules)Digestion of Proteins to peptones.Digestion of starch.Splits fats into fatty acids and glycerol.

4. Jejunum & Ileum

Intestinal juice succus entericus (contains enzymes to digest proteins, fats & carbo-hydrates completely.

1. Protein

2. Fats

3. Carbo- hydrates

Proteins & peptones to amino acids.Fats to fatty acids & glycerol.Maltose & other carbohydrates to glucose.

Respiration:- (A) Breathing :- Exchange of gases CO2 and O2.(B) Cellular Respiration :- Oxidation of digested food for release energy. It takes place in

mitochondria.

Types of Respiration:- Aerobic Respiration- Food is completely broken down into carbon dioxide and water with the help of oxygen. Glycolysis Kreb’s Cycle (In mitochondria)

Glucose Pyruvate CO2 + H2O + 36ATP No O2 required (ETC)

(In cytoplasm)

Anaerobic Respiration- Food is broken down in the absence of oxygen to release energy. Ethyl alcohol is the end product in plants and lactic in muscles of animals.

(i) In yeast :- Glycolysis Fermentation

Glucose Pyruvate C2H5OH + H2O + ATP No O2 required In absence of O2

(ii) In Muscles :- In muscle

Glucose Pyruvate Lactic acid + H2O + 2ATP

Aerobic Respiration Anaerobic Respiration1. Uses oxygen. 1. Does not require oxygen.2. End products are CO2 & H2O. 2. Ethyl alcohol or lactic acid is formed.3. A lot of energy is released. 3. Very less energy is required.


SARASWATI STUDY POINT4. Example – All animals & plants with exceptions.

4. E.g. – In our muscles during exercise – formation of lactic acid.

Yeast – Formation of alcohol used in the manufacture of alcohol. Respiration in plants:-

(i) Root, stem, leaves all perform respiration individually.(ii)Transport of oxygen from one part to another in little.(iii)Plants respire slower than animals(iv) Exchange of gases in roots, stems and leaves by diffusion.

Gaseous exchanges through Stomata present in the leaves lenticles present in the stems and bark of old trees root hair, in roots absorb oxygen by the process of diffusion.

Respiration in animals:-There are specific organs for respiration in animals.

(a). Amoeba: Respires through the body surface by the process of photosynthesis.(b). Insects: Tracheal system of air tubes (grasshopper, cockroach, and housefly).

Path of air Spiracles Trachea Tracheoles CellsProcess:-

(i) Air is taken in through spiracles passed into air tubes which branch into a network of tracheoles.

(ii)Oxygen is absorbed by cell and is used to oxidise the food.(iii)Carbon dioxide is expelled out through these tubes (tracheoles).(c). Earthworms: The wet skin by diffusion.(d). Amphibians:- Respire through moist skin and lungs (frog).(e). Aquatic animals:- Use gills as the respiratory organs (fish, prawn). Blood flowing in the

gills absorbs oxygen and gives carbon dioxide into the water through diffusion.

(f). Land animals:- Lungs (Frog, birds and human etc.)

Respiration in human beings:- Takes place in three steps (i) Breathing:- It involves intake of oxygen and exhalation of carbon dioxide.(ii)Exchange of gases in tissues:- Due to difference in concentration in the tissues, the gases

get exchanged between tissue and blood capillaries.(iii)Oxidation of simple food molecules like glucose for release of energy in the mitochondria

of cells.

Three common features of Respiratory organs:-(i) Large surface area.(ii) Thin walls (for easy diffusion).(iii) Hare rich blood supply.


SARASWATI STUDY POINT Respiratory Organs:- Nostrils, Nasal cavity, Pharynx, Trachea or wind pipe, Bronchi, Alveoli or air sacs of lungs.

Steps of respiration:-

(i) Nostrils take in air.(ii) Air passes through Nasal Cavity. Air is warmed and moistened. Dust Particles and

foreign bodies are trapped in the hair and mucous.(iii) From internal nostrils air enters into pharynx.(iv) Glottis – A slit through which air enters from pharynx into trachea. Epiglottis is a small

flap that prevents the entry of food into the windpipe.(v) Trachea divides into bronchi. Larynx or voice box is situated at the beginning of the

trachea. It has two stretched cords called vocal cords which on vibration produce voice.Adam’s apple is enlarged larynx, formed by procartilage).

(vi) Bronchi divide into bronchioles which end into alveoli in the lungs.(vii) Oxygen from air diffuses into the blood capillaries surrounding the lungs.(viii) Carbon dioxide from the blood diffuses in the lungs.(ix) Lungs contract and give out carbon dioxide rich air through nostrils.

Air Nostrils Pharynx Wind pipe Bronchi Lungs Alveoli Blood Tissues

(The whole process takes place in presence of oxygen and carbon dioxide). (Oxygen is inhaled and carbon dioxide is exhaled).

Mechanism of Breathing


Inhalation Exhalation1. Air rich in oxygen is taken in from outside.

1. Air rich in carbon dioxide is breathed out.

2. Rib muscles contract. 2. Rib muscles relax and expand.3. Diaphragm contracts. 3. Diaphragm relaxes.4. Thoracic cavity expands increasing its volume.

4. Volume of thoracic cavity is decreased.

5. Decrease in air pressure inside the lungs.

5. Increase in air pressure inside the lungs.

6. Air from outside rushes into the lungs. 6. Air is breathed out of the lungs.

SARASWATI STUDY POINT Transportation: - A life process in which a substance absorbed or synthesized in one part is

moved to another part of the body.

Transportation in plants:-

(i) Transportation of water and minerals – (a) Water and minerals move up to the leaves from roots through tracheids and vessels – the

two elements of xylem. They are non-livings thick walled, long spindle shaped. Non-flowering – Tracheids flowering – Tracheids and vessels.

(b) Transportation of water from leaves creates a pull (suction) and helps in the upward movement of sap or water.

(c) Movement of water molecules (path).Water Root hairs Epidermis of roots Cortex Endodermis Root Root – Xylem Xylem in stem Xylem in petioles Leaves.

(ii)Transportation of food and other substances – (Translocation)It is done through phloem by the action of living cells called sieve tubes. Food enters from mesophyll cells of the leaf. Materials to be transported:-(a) Food (sugar), metabolites synthesized in leaves and hormones synthesized at the shoot and

root tips.(b) Translocation transport of food from leaves to other parts of the plant by phloem.

(iii) Transporting fluids – (1). Blood (2). Lymph

Functions of blood:-

(i) Transports nutrients, hormones, excretory products, respiratory gases from one part to other part of the body.

(ii) Maintains the body temperature constant.(iii)Protein in the plasma helps in coagulation (clotting) of blood.(iv) Haemoglobin in RBCs carries oxygen from lungs to tissues and carbon dioxide from tissues

to the lungs.(v) WBCs fight against germs.(vi) Antibodies in plasma defend the body against diseases.

Red blood corpuscles:-

(i) Contain Haemoglobin in (red colour pigment). This gives red colour.(ii) Haemoglobin in RBCs carries oxygen from lungs to tissues and carbon dioxide from tissues

to the lungs.(iii)Formed in bone marrow.


SARASWATI STUDY POINT(iv) Life span 120 days.(v) Mature RBCs do not have a nucleus.

White blood corpuscles:-

(i) Colorless and less in number compared to white blood cells.(ii) Protect the body from infections.(iii)Manufacture antibodies responsible for immunity.(iv) Formed in bone marrow.

Blood Platelets:-

(i) Help in clotting of blood.(ii) These cells do not possess nuclei.(iii)Manufactured in the bone marrow.

Plasma:- It contains 92% of water and 8% many proteins and many solutes which include hormones, vitamins, glucose, fatty acids, enzymes, antibodies waste products such as urea.

Blood Vessels:-

Arteries Veins1. Thick walled. 1. Thin walled.2. Carry blood from the heart to different parts.

2. Carry blood from the different parts to the heart.

3. Carry oxygenated blood except pulmonary arteries.

3. Carry deoxygenated blood except pulmonary veins.

4. They are deeply situated. 4. They are superficially situated.

Capillaries:-

(i) Very thin walled and narrow tubes.(ii) Connect arteries and veins.(iii)Exchange of gases and food materials in tissues takes place through them.

The Human Heart:-

(i) Heart is four chambered.(ii) It has two upper chambers (Atrium) and two lower chambers (Ventricles).(iii) Heart is made up of special muscle cells – cardio muscle fibres.(iv) Heart beats all the time throughout one’s life.(v) Heart beat is due to the rhythmic contraction and relaxation of heart muscles.


SARASWATI STUDY POINT(vi) An instrument, called electrocardiograph can record electrical changes during heart beat.

This graphic recording is called ECG or electrocardiogram.(vii) “Pace Maker” a special machine can be used in patients whose specialized muscle cells

have stopped functioning leading to abnormal heart beat.

Functioning of Heart:-

(i) Deoxygenated blood from various parts of the body is poured into right atrium by the large vein (vena cave).

(ii) Oxygenated blood from lungs is brought into left atrium by the pulmonary vein.(iii)Both atrium contract and pour blood into both ventricles.(iv) Next both ventricles contract and

(a) Oxygenated blood from left ventricle is distributed to all parts of body through the largest artery also.

(b) From right ventricles deoxygenated blood is carried by the pulmonary artery to the lungs for purification.

(v) This process keeps on repeating. During this process as blood flow in and out of the heart twice the circulation is called double circulation.

Lymph:-

(i) A light yellow fluid oozes out of the porous walls of capillaries and bathes the cells.(ii) Contains Lymphocyte cells that fight against infections.

Lymphatic System:-

(i) Consists of the circulatory fluid Lymph, lymphatic capillaries, lymph vessels, lymph glands and lymph nodes.

(ii) Lymph flows in one direction that is from tissues to heart.

Functions of lymph:-

(i) Carries the large plasma proteins and fluid from the tissues into the blood.(ii) Carries digested fats.(iii)The lymphocytes fight against infection.

Excretion:-

Purpose:- (i) Removal of excess of toxic wastes from the body.(ii) Osmoregulation – Maintaining sight amount of water and proper ionic balance in the body.

Excretion in animals:-1. Amoeba – By simple diffusion through contractile vacuole.


SARASWATI STUDY POINT2. Hydra & Sponges – Diffusion through oral opening called osculum.3. Earthworm – Nephridia and through moist skin.4. Flat Worm – Flame cells.5. Human beings – Kidneys.

Excretion in Human beings:-

Organs – Two Kidneys, two ureters, Urinary bladder, Urethra and Urinary aperture. Mechanism:-

(i) Renal arteries bring waste material to the kidneys.(ii) Blood is filtered from the glomerulus into Bowman’s capsule of the nephron.(iii)Filtrate from blood passes through the tubules of the nephron.(iv) Useful products like glucose, amino acids are reabsorbed from the filtrate into blood.(v) Urine is drained from the nephron into ureters.(vi) Urine passes into urinary bladders and thrown out.

Osmoregulation: - The process of maintaining right amount of water and proper ionic balance in the body.

Dialysis:- In case of kidney failure, blood is made to flow into dialysis machine made of long cellulose tubules coiled in a tank having dialyzing solution waste substances diffuse out of blood into tank. Purified blood is pumped back into the patients’ body.


SARASWATI STUDY POINTQuestions

1. What is the mode of nutrition, when organism use simple substances like CO2 and water to prepare food inside the body?

2. Name one enzyme secreted by salivary glands as well as pancreas.3. What is the name given to rhythmic wave like manner occurring in alimentary canal?4. Name one basic element of food essential for all living organisms.5. Name one organism which shows anaerobic respiration.6. What is lymph?7. Write down the chemical equation showing and products of photosynthesis.8. Name the type of respiration in which no oxygen is needed from surroundings.9. In most organisms, the complex substances are taken as food from outside and then broken

down into simpler one by use of biocatalysts. What is this mode of nutrition called?10. What are enzymes?11. What is the name given to those cell organelles which contain green pigment. Name this green

pigment also.12. Name the process by which energy is obtained by living organisms.13. Name the cells which regulate the opening and closing of stomata.14. Expand ATP.15. Why hairs are present in nasal chamber?16. Name the intermediate 3 carbon molecule formed from six carbon molecule of glucose during

respiration.17. What is the impact of leakage or loss of blood upon the pressure?18. Name the air sacs in which bronchioles terminate.19. What is the site in cells where glucose is converted into 3 carbon molecules of pyruvate?20. Why rings of cartilage are present in trachea in throat region?21. What products are formed during respiration in our muscles when there is less supply of

oxygen?22. Which component of blood prevents the loss of blood? Also, name the process by which it is

prevented.23. Name the cell organelle where pyruvate breaks down, using oxygen.24. Name the part of digestive tract where complete digestion of carbohydrates, proteins and fats

occur.25. From where do the terrestrial animals get oxygen for respiration?26. Name the pigment present in blood of higher animals which supply oxygen to all tissues for

respiration.27. Name the muscles of stomach which regulate the release of food from stomach to small

intestine.28. Only visible movement can be used as the defining character for life. Give reasons.


SARASWATI STUDY POINT29. What is the range of pH in small intestine and stomach respectively?30. How does the bile juice help in digestion of fats?31. Explain double circulation in human beings.32. Why is the rate of respiration in animals faster and higher compared to respiration in plants?33. The molecular movements inside the body of living organisms help them in survival. How?34. Name the two glands associated with intestine common duct. Also name their secretions.35. Herbivores have a longer small intestine as compared to carnivores. Explain in brief.36. Why purification of blood is also referred to as gaseous exchange?37. Name the chemical compound associated with fermentation and anaerobic respiration in

muscles.38. After purification of blood concentration of which gas increases in Blood Alveoli?39. Write two important functions of transpiration in plants?40. Give two main functions of HCl present in gastric juice.41. Name the substances transported by phloem.42. What are the two reasons for which plants have low energy needs?43. After a long walk, a person suffers from muscular cramps. What can be possible reasons for

this observation? Name the process involved.44. Express the movement of sucrose in phloem.45. Draw a labelled diagram of a transverse section of leaf.46. Select from the following, the organism in which oxygenated and deoxygenated blood mix:- Lizard Snake

Rat Pigeon Dog Whale

47. Enlist the various ways by which plants get rid of their waste products.48. Describe the significance of circulatory system in human beings.49. Write down three main steps of photosynthesis.50. Describe mode of nutrition in Amoeba with the help of a diagram.51. Rahul suggested Shashi that food in the stomach is not yet in the body. Do you endorse Rahul’s

view? Give reasons in support of your answer.52. Write the functions of muscular wall in digestive tract.53. Name the components of gastric juice. What are their functions?54. Define the following terms:- (i) Anaerobic respiration (ii) Anaerobic respiration

Which of the two is energy efficient?55. Describe the urine formation in human beings. Draw a neat and labelled diagram of nephron.56. Briefly mention the circulation of blood in human heart with the help of a labelled diagram.57. Explicate the association between nutrition, respiration, transportation and excretion in

multicellular organisms. 58. Define autotrophic and heterotrophic nutrition?59. What is difference between saprophytic and Holojoic Nutrition?


SARASWATI STUDY POINT60. What is the size of chloroplast? Where does it located?61. What is the use of chlorophyll in plants?62. What is the range of light which used by plants for photosynthesis?63. What are the difference between chlorophyll and chloroplast?64. By which process plant absorbs water?65. How will you prove that CO2 is necessary for photosynthesis?66. IN which colour of light photosynthesis will be minimum and why?67. Describe Absorption spectrum with Graph?68. Define Nutrient and Nutrition.69. What’s the source of free oxygen in Photosynthesis? 70. What is function of the liver? 71. Define glycolysis?72. Explain the mechanism of Aerobic & Anaerobic Respiration? 73. Explain mechanism of Breathing?74. Differentiate between absorption and assimilation. 75. Explain why more amount of energy produced in aerobic respiration?76. There is no need of respiratory system in amoeba why?77. Give difference between peprin and tripin? 78. What are secretion points of amylase?79. What is the other name of “Voice Box”?80. Why do the walls of trachea not collapse when the is less air in it?81. State function of mucous membrane inside the nosal passage.82. How is epiglottis differing from glottis?83. Describe the proper sequence the digestion of (a) Proteins (b) Fats (c) Carbohydrates84. What are the end products of light Rxn?85. Draw alimentary canal of man?86. Where does digestion begins in humans?87. Name the structures through which amoeba captures food.88. Why land plants die if their roots remain water logged?89. How voice produced in Voice Box?90. What are common feature of Respiratory organs of animals.91. What are stomata and Lenticlas?92. State the function of Epiglottis?93. What is the need of Bile and HCl?94. What are secretion points of amylase?95. Why one should not talk while eating?96. What is Adam’s Apple?97. What are thylakoids?98. Name the membrane covering the lungs?


SARASWATI STUDY POINT99. How many types of xylem found in plants?100. Write a short note an xylem?101. Which type of xylem found in non-flowering & flowering plants?102. In which form minerals taken by plants & from where it enter in the roots?103. How are mineral transport in plant body?104. What do you mean by transpiration?105. How transpiration helps in upward movement of water?106. Define Translocation?107. Write short note on Phloem?108. Give Difference between xylem and Phloem?109. Show by diagram pathway of water inside root.110. Name three types of blood vessels & give difference in them?111. Write a short note on Plasma?112. What is the other name R.B.C and W.B.C?113. Define Immunity?114. How W.B.C help in Immunity?115. Write a short note on Blood?116. In which part of body cells are formed?117. Draw Heart?118. What do you mean by double circulation?119. Write a short note on lymphatic system?120. Which fluid is also known as extra cellular fluid?121. Give difference between blood & lymph?122. Why vein have thin walled & artery have thick walled?123. What is the average life span of R.B.C.?124. What is the function of value?125. What is RH factor? What is its significance?126. Differentiate between R.B.C and W.B.C?127. Describe the structure of nephron with figure?128. Describe the excretory system of man?129. Write excretory unit of Amoeba sponge, Hydra, Flatworm Earthworm?130. Which is major waste produced in human being? How it is remove from the body?131. What is Osmoregulation? How does it take place in human? 132. Describe the formation of urine in man?133. Give difference between ureter & urethra?134. What happens when glucose which enters the nephron along with the filtrate?135. How can you say that excretion is affect by environment?


SARASWATI STUDY POINTControl & Co-ordination

Control & Coordination is done by- (i) Nervous System (ii) Hormonal SystemAll living organism respond and react to their environment.

Phytohormones: - Control & Coordination between plants and their environment is done by chemical substances called Phytohormones.Examples: - Auxins, Gibberellins, Cytokinins, Abscisic acid and Ethylene.

Tropism: - The movement of plant in the direction of the stimulus. Phototropism: - Stimulus – Light, E.g., Stem bends and grows towards the sources of light. Geotropism: - Stimulus – Gravity, E.g., Roots curve towards the force of gravity. Chemotropism: - Stimulus – Chemicals, E.g., Growth of Pollen tube in flower. Nastic Movement: - Movement neither towards nor away from stimulus. E.g., folding of the

leaves ‘Touch me not’ Plant. Photoperiodism: - Flowering and seed germination is regulated by duration of light is called

Photoperiodism. It is controlled by chemicals called Phytochromes. Functions regulated by Phytohormones:-

(i) Growth of root, stem, leaf.(ii) Flowering.(iii) Ripening of fruit.(iv) Breaking seed dormoney and including the seed to germinate.(v) Tropic movements.(vi) Development of seedless fruit (Parthenoearpy) E.g. Grapes.

1. Occipital lobe – Visual reception.2. Temporal lobe – Auditory reception.3. Frontal lobe – Muscular activities.4. Parietal lobe – Touch, smell, temperature & conscious association.

Neuron:- Structural & functional unit of nervous system is called neuron (nerve cell). Parts of Neuron:-

1. Cyton (cell body) – Typical cell with nucleus and granule or cytoplasm.2. Axon – Single large elongated fibre arises from cyton & carry impulses from neuron.3. Dendrites – Short and branched processes arising from cyton & carry impulses to the cyton.4. Synapse – The functional junction or connection between two neurons.5. Nerve Impulse – Chemical & electrical signals that pass through neurons.

Central Nervous System:-The central Nervous system consists of two parts:-


SARASWATI STUDY POINT(i) Brain (ii) Spinal Cord

Brain: - It is protected by brain cranium covered by meanings which is filled by cerebrospinal fluid acts as shock absorber.

Cerebullum: - Coordination and adjustment of movement and pasture.

Medulla Oblongata: - Involuntary movement, swallowing, sneezing, coughing, vomiting. Pons: - Regulation of respiration.

Spinal Cord:- Cylindrical structure begins in continuation with medulla oblongata and extends downward, well protected in Vertebral Column.

31 pairs of spinal nerves (sensory & motor nerves) arise from the spinal cord and control the body functions.Spinal cord is responsible for reflex action.

Reflex action:- It is a spontaneous automatic and quick response to a stimulus without involving the brain. Here the orders are given by the spinal cord.

e.g., Withdrawal of hand when we touch a hot object.

Reflex arc:- The path of reflex action.(i) A receptor to perceive the stimulus (touching a hot object).(ii) A sensory nerve that carries the message from the sense organ to the spinal

cord.(iii) Neurons of the spinal cord process the stimulus and transmit the order to the

motor neuron.(iv) Motor neurons carry the message (order) to the effector organs.(v) Effectors organ (muscles & glands) respond to the stimulus

Stimulus Receptor organ Sensory organs Spinal cord Motor neurons Effector organ Response

Chemical Coordination:-Hormones: - It was introduced by Bayliss.

Hormones are chemical substances secreted in trace amount by Specialized tissues called Endocrine glands.

(i) Chemical messengers (substances) secreted in traces by endocrine glands.(ii) Hormones are poured directly into blood and carried by blood.(iii)They acts as specific organ called target organs.

Functions of Hormones:-


SARASWATI STUDY POINTEndocrine glands Hormones Functions1. Hypothalamus Releasing hormone Regulates Pituitary.2. Pituitary (Hypophysis)

Growth hormoneTraphic hormone

Growth of bones & muscles.Stimulate other endocrine glands.

3. Thyroid Thyroxin Metabolism of carbohydrate, fat & proteins.

4. Parathyroid Calcitonin Regulate blood calcium phosphate.5. Adrenal Adrenaline corticoids Regulate blood pressure and heart

rate.6. Pancreas Insulin, Glucagons Regulate sugar metabolism.7. Testes Testosterone Gametogenesis and secondary sex

characters.8. Ovary Estrogen & Progesterone Gametogenesis feminine characters.

Questions

1. Name the part of brain in which hypothalamus is located.2. Arrange the following sequence on the basis of their location from mid brain: Spinal cord,

pons and medulla.3. Ranveer rides a bicycle maintaining posture and body equilibrium. Identify the part of brain

which controls this activity?4. What is synapse?5. How is brain protected from shocks and injuries?6. What part of brain is concerned with memory?7. Define reflex action.8. Name the neuron that links motor and sensory neurons.9. Which part of the brain is responsible for precision of voluntary action?10. Why is salvation considered to be an involuntary action?11. What is the impact of nervous electrical impulse upon muscle proteins?12. Name any one movement of ours which occurs in order to protect ourselves.13. Gustatory and olfactory receptors related to which sensations?14. Name the most important organ related to control and coordinate our activities?15. Which part of the brain would you associate with smell of delicious food?16. Where is aurin synthesized?17. Where is the adrenal gland in your body located?18. How our growth is associated with thyroxin?19. Name two plant hormones that help in stem growth?20. Name the place of origin of cranial nerves.21. What could be the possible disadvantages of reflex action were controlled by the brain?22. Movement of which chemical compound help plants in changing shape?


SARASWATI STUDY POINT23. Write the name of two hormones responsible for bodily changes in boys and girls around the

age of 10-12 years.24. Which of the two is slower-growth dependent or growth independent movement in plants?25. Identify the system which facilitates the communication between the central nervous system

and other body parts?26. Write the components of Peripheral Nervous system?27. Write the name of the thinking part of the brain?28. Which two organs receive the information from all body parts and integrate it?29. What is the effect of adrenalin on the rate of breathing of heart?30. Upon adrenalin movement along with blood stream the blood supply to which two body parts

is reduced?31. Which nutrient of food is associated with muscular action?32. A doctor advised a patient to take less sugar in her diet. Which disease is she suffering from?

Which body organ and connective tissue is related with it?33. An element of halogen family is compulsorily added to common salt in small quantity.

Identify the element. Also name the disease caused by its deficiency and write one symptom of their disease.

34. Enlist the functions of medulla.35. How is spinal cord related to the efficiency of reflex arc?36. How is iodine important for biochemical reaction inside the body?37. What consists thinking tissue? Where is it located?38. What are the two limitations of electrical impulses?39. Enlist one advantage and one limitation of chemical communication.40. Draw a labelled diagram of neuro-muscular junction.41. Describe the feed back mechanism.42. Draw a neat and well labeled diagram of human brain.43. Enlist the hormones secreted by ovary testes and adrenal gland. Write one function of each

hormone.44. Tendril encircles or coils around the objects in contact with it. Elaborate.45. How plants communicate the information of touch as stimulus as in touch-me-not plants.46. Elaborate the body’s response to adrenalin secretion into the blood.47. Define a reflex arc. Draw its labelled diagram.48. Write major functions of three parts of the brain.49. Briefly describe the three parts of the neuron.50. Elucidate the nerve impulse mechanism.51. Define plants hormones; write the important functions of the following: auxin, abscisic acid,

gibberellin and cytokinin.52. Describe different tropic movements with suitable example.


SARASWATI STUDY POINTElectricity

Important terms and definitions:-

Coulomb’s Law:- The electrostatic force of attraction or repulsion between a pair of charges is directly proportional to the product of the charges and inversely proportional to the square of the separation between them, i.e.,

F q1q2 or F = Kq1q2

r2 r2

Where K, the constant of proportionality has a value of 9 109 Nm2 / C2 for free space.This force acts along the line joining the two charges. If the charges are similar, then there will be repulsion and so force will be positive. If the charges are dissimilar, there will be attractive force and so the force will be negative.

Charge Conservation: - When a glass rod is rubbed on silk, we say that the glass rod acquires positive charge. But it is not created. The negative charges from glass rod are shifted to silk leaving a net positive charge on glass rod.

Difference between Charge and Mass:-Mass Charge

1. Always remains positive. 1. Can be negative or neutral also.2. Gravitational force of attraction exists between them.

2. Electric force of attraction or repulsion exists.

3. Expressed in kilogram. 3. Expressed in coulomb.

Charge: - Electrons have a negative charge of 1.6 10-19 while protons have an equal positive charge of 1.6 10-19 C.

Insulators: - Insulators do not conduct charges, they can be charged easily by friction. The charges remain localised in them.

Conductors:- Substances in which charges can flow freely are called conductors while an insulator in one in which free motion is not possible.

Current:- The rate at which the charges move is called current, i.e., the quantity of charge in coulomb crossing a point in unit time is called electric current. We write it as I = q/t, where q – the charge is expressed in coulomb and t – time is expressed in second. Current is written in coulomb-per-sec or Cs-1 or ampere in S.I. system (in honour of French scientist Andre-Marie Ampere).

1 A = 1 coulomb (C) = 1 Cs-1

1 sec (s)Small units of current are

1 mA = 10-3 A (mA = milliampere)1 A = 10-6 A (A = microampere)PITAM PURA & ROHINI (www.saraswatichemistrypoint.com) 011-27316087 / 9899899326 28

SARASWATI STUDY POINTCurrent is a scalar quantity, even though it is the flow of positive charges

(Conventional current – Opposite to the direction of flow of electrons). This is because, (i) Currents, are added algebraically in any circuit and (ii)Current remains same even if the cross-section varies along the length or any bend in the

wire.Current may be direct, varying or alternating current.

Electrical Potential:- Charge motion exists only when energy is available. Electrically we call it as creation of electric potential difference. Electric potential is defined as the work done in carrying a unit positive charge from infinity to a point against any electric field. Electric potential V is given by V = W/q. It is expressed in volt or joule/coulomb.

Electric Potential Difference:- Every point surrounding a charge will have electric potential. When a charge of 1 coulomb is carried from one place to another, the work done is called as electric potential difference. Electric potential difference between two points A and B is, therefore, given by,

VAB = Work done to carry a charge q from A to B Charge q in coulombs

It is expressed in volts.1 volt = 1 joule or 1 V = 1 J

1 coulomb 1C

Meters:-

Voltmeter Ammeter1. Used to find potential difference 1. Used to find current.2. Should be connected in parallel. 2. Should be connected in series.

Ohm’s Law: - Under similar physical conditions, the current flowing through a wire is directly proportional to the difference in potential applied across the ends, (i.e.) I V or V = IR where R is the resistance offered.Graphically, it can be shown by the line below:Slope (V/I) is a measure of resistance offered.

Ohm: - It is the S.I. unit of resistance. It is in honour of the German physicist Georg Simon Ohm (). One Ohm is that resistance offered by the wire carrying 1A of current when 1V is applied across the ends.

1 ohm = 1 volt (or) 1 = 1V 1 ampere 1A

Resistance: - The opposition caused to the flow of current is called resistance. It is denoted by the symbol “__” in an electrical circuit and is expressed in ohm. It is a property of the wire used in the circuit. Conductors offer low resistance while insulators offer large resistance.

Factors affecting Resistance:- Resistance of a conducting wire depends on :PITAM PURA & ROHINI (www.saraswatichemistrypoint.com) 011-27316087 / 9899899326 29

SARASWATI STUDY POINT(i) nature of material (Resistivity-)(ii) length of the wire (l) and (iii) the cross-sectional area of the wire (A).

R = _l_ gives the exact relation. A

Resistivity ():- The resistance offered by a wire of unit length and unit cross-sectional area is called Resistivity. It is expressed in terms of ohm-metre (-m). For a material irrespective of length and area, the Resistivity is a constant. It is otherwise called specific resistance of the material. It is also defined as the resistance offered by a cube of a material of side 1m when current flows perpendicular to the opposite faces. Metals and alloys have low Resistivity, while insulators have high Resistivity. Reciprocal of Resistivity is called conductivity. Conductivity, = 1/ and is expressed in mho-m-1 or ohm-1 m-1.

Rheostat:- It is a device which changes the magnitude of current in the circuit, by changing the resistance. It is connected in series in the circuit. It is also used as a potential divider in circuits.

Wires in Electrical Appliances:- Alloys have higher Resistivity than pure metals and they also show less rapid variation of Resistivity with temperature. They do not oxidise or burn readily at high temperatures. So they find utility in heating devices like electric iron, toasters, etc. copper and aluminium wires are used for transmission of signals. Tungsten is used for exclusively for filaments in incandescent lamps.

Resistance is Series:- When resistors are placed in series :(i) The current through them will be the same.(ii) The sum of the potential difference or voltage across them is the total potential difference

(i.e.,)V = V1 + V2 + V3 = I (R1 + R2 + R3)

(iii) the equivalent resistanceRS = R1 + R2 + R3

(iv) Can be identified when one common point not connected with a third device is seen. Resistance in Parallel:- When resistors are connected in parallel :

(i) the potential difference across their ends is the same,(ii) the sum of the current through them is the current drawn from the source of energy or cell.(iii) the equivalent resistance is found by 1 = 1 + 1 + 1

RP R1 R2 R3

(iv) Can be identified when two common points between resistors exist.In parallel circuit shown here,

I = I1 + I2 + I3

V = V + V + V RP R1 R2 R3 1 = 1 + 1 + 1

RP R1 R2 R3


SARASWATI STUDY POINT Electrical Energy:- Since there exists resistance to the flow of current, work has to be done in

order to maintain the flow of current. Since potential difference V is the work done to carry unit positive charge from infinity to a point, the work done to carry a charge q is given by,W = qVSince, I = q/t q = It

W = ItVSince, V = IR, W = I2Rt = V2t/R

This also proves the joule’s law of heating. Toasters, Irons and Electric stoves, Heat convectors use this energy. Tungsten filaments used in incandescent lamp operate at a temperature of 2700C. Both heat and light energy are evolved from this lamp.

Joule’s Law of Heating:- When a current I flows through a resistor R, heat is produced. The heat produced H depends directly on the square of the current, resistance and the time t for which the current is allowed to pass through.

H = I2RtThis is called Joule’s law of heating.

Electric Power: - The rate at which electric energy is consumed is called electric power. Power = Work done = W; Power = VI = I2R = V 2 = q V Time t R tPower is expressed in joule/second or watt.When 1 ampere current is passed through a resistor of 1, the heat energy produced is, 1 joule. If this flow is maintained for 1 second, the power consumed is 1 watt.

Kilowatt hour:- kWh is the commercial unit for electrical energy.1 kWh = 1000 Wh

= 1000 joule 3600 second second

= 3.6 106 joule.

Some larger units of Power:- 1 kilowatt (kW) = 1000 watts = 103 watts 1 megawatt (MW) = 106 watts Horse Power is the unit of power generally used in engineering industry and 1 horsepower

(hp) = 746 watts.

Filament in Bulbs: - Made of metals with high melting point (3380C for Tungsten). They are thermally insulated with insulating supports. Presence of inactive gases like nitrogen and argon prolongs their life.

Fuse Wire:-

The wire which melts breaks the circuit and prevents the damage of various appliances in household connections.

It is connected in series and its thickness determines the maximum current that can be drawn.


SARASWATI STUDY POINT It is made of an alloy of Aluminium, Copper, Iron and Lead. It should have high resistance and low melting point. It is generally encased in a catridge of porcelain or similar material with metallic ends.

Depending on the device/appliance used, the fuse wire of proper thickness has to be used.[ I r3/2 and I drawn = Power of device ]

Voltage applied

Fuse wires with varying capacity are available. The thickness of the wire increases the maximum safe current that can flow through it. In India fuse for a current of 5A and 15A is used. For heavy appliances like geyser, heaters, etc., 15A fuse wire is used, but for fan, light and many other light equipments 5A fuse wire is used. It is not proper to put a highly thick wire for low current appliances, since the equipment may be damaged as a result of higher current.

Questions1. Define electric current & write its S.I unit.2. How many electrons are there in one coulomb of charge?3. Draw symbol for (a) cell (b) switch.4. What is the S.I unit of charge? Define it.5. Define potential difference (P.D.) & write its S.I. unit.6. Two wires of same material and cross-sectional area of length 10cm & 20 cm. Which will have

more resistance?7. Name the instrument used for measuring (a) Potential difference (b) Current.8. How will you connect voltmeter & ammeter in electric circuit?9. Name one gas filled in bulbs.10. What is resistance? Give its S.I. unit.11. Name the component used to regulate current without changing the voltage.12. Two wires of same material & cross-sectional area of length 10cm & 20 cm. Which will have

more Resistivity?13. Name the instrument used to change the resistance of the circuit.14. The area of cross-section of wire P is doubles that of Q (of some material & length). Which

will have more resistance?15. The area of cross-section of wire P is doubles that of Q (of some material & length). Which

will have more Resistivity?16. Define 1 joule.17. What is Ohm’s law?18. Which material is used for domestic electric wiring? Give example.19. Define 1 watt.


SARASWATI STUDY POINT20. Under similar physical conditions for resistance, what is the relation between voltage (P.D) &

current?21. Define Electric power. Write its S.I. unit.22. Give one property of fuse-wire.23. Give one example of material used in fuse wire.24. Under similar physical conditions if the P.D. across the wire is double. What will happen to its

current?25. What is commercial unit of energy?26. Write the relationship between commercial unit & S.I. unit of energy?27. Name two appliances where heating is undesirable.28. Why do we encase the fuse wire in a cartridge of porcelain or similar material with metal end?29. Where does energy of the source go, when the circuit is purely resistive?30. Why do we use alloy in Electric iron toaster.31. Why do we use tungsten while constructing a bulb?32. What is the function of rheostat?33. Give two examples where energy of the source is purely used in resistive circuit.34. Why do we fill gas in a bulb? Give example.35. Out of current & potential difference, which remains same through:-

(i) A series combination (ii) parallel combination36. One wire is cut into three equal parts and then connected in parallel, how will:

(a) Resistance (b) Resistivity get affected.37. How should one connect there resistance if values 2Ω, 3Ω & 5 ohms to get resultant resistance:

(a) more than 5 ohms. (b) Less than 5 ohms.38. Out of two fuse wire A & B with current rating 2A & 5A which would be selected for use with

a 1000W; 200V room heater. Justify your answer.39. An electric iron is marked 660W & 220V. What would be:-

(i) Current drawn by the filament.(ii)Resistance of the filament.

40. How many electrons will flow for charge of 2C.?41. 8 ohm resistance produces 200J heat each sec. Find the potential difference across the resistor.42. An electric iron consumes 1kW electric power when operated at 220V; calculate the value of

fuse wire one should use in such case.43. What are the disadvantages of series arrangements for household circuits?44. Why do we use parallel circuit arrangements for domestic wiring?45. On what factors do the resistance of the material depends.46. State Ohm’s law. Draw circuit diagram for its verification.47. An electric heater connected to a 22V line has two resistance coils, each of 22ohms resistance.

They may be used separately, in series or in parallel. What are the currents in these cases?


SARASWATI STUDY POINT48. A lamp of 100W at 220V & other of 60W at 220 are connected in parallel to electric mains

supply. Calculate the total current drawn from the line.49. A heater wire whose power is kW is connected 220V source. Calculate:-

(i) Electric current in the circuit.(ii)Energy consumed in 2 hours.

50. In which of the following case energy consumption is more(i) A 250W T.V set runs for one hour.(ii)An electric iron of 1000W is used for 10min.

51. A 400W refrigerator operates for 16hrs/day; calculate the cost to operate it for 30 days at Rs3 per kW hr.

52. State the law which governs the strength of current & potential difference applied across conductor. Illustrate the law graphically.

53. Calculate:-(i) Resultant resistance.(ii)Total current.(iii) Voltage across 7 ohms resistor.

Some Extra Questions: -

1. What is the S.I. unit of electric potential?2. What is meant by the statement, “Potential difference between points A and B in an electric

field is 1 volt”?3. There are two electric bulbus (i) marked 60 W, 220 V and (ii) marked 100 W, 220 V. which

one of the two has a higher resistance ?4. Out of the two, a toaster of 1 kW and an electric heater of 2kW, which has a greater

resistance?5. Name a metal which offers higher resistance to the passage of electricity other than copper.6. Which has a higher resistance : a 50 W lamp bulb or a 25 W lamp bulb and how many times?7. Why is tungsten metal selected for making filaments of incandescent lamb bulbs?8. A wire of resistance 10Ώ is bent in the form of a closed circle. What is the effective

resistance between the two points at the ends of any diameter of the circle?9. Should the heating element of an electric iron be made of iron, silver or nichrome wire?10.Define the term “resistivity’ of a material.11.Calculate the resistance of a conductor, if the current flowing through it is 0.2 A when the

applied potential difference is 0.8 volt.12.A cylinder of a material is 10 cm long and has a cross-section of 2 cm2. If its resistance along

the length be 20, what will its resistivity value be in number and units?13.A wire of uniform area of cross section is stretched to four times its original length. By what

factor does its resistivity change?


SARASWATI STUDY POINT14.If a wire of resistivity (p) is stretched to thrice its initial length, what will be its new

resistivity ?15.Which has a greater resistance 1 kW electric heater or a 100 W filament bulb both marked for

220 V?16.A heater joined in parallel with 60 W bulb is connected to the mains. If the 60 W bulb is

replaced by a 100 W bulb, will the rate of heat produced by the heater be more or less or remains the same?

17.Nichrome and copper wires of same radius are connected in series. Current I is passed through them. Why does the nichrome wire get heated first?

18.Two bulbs are marked 60 W, 220 V mains. Which one of the two will glow brighter?19.A toaster produces more heat than a light bulb when connected in a parallel to the 220V

mains. Which of the two has greater resistance?20.Two bulbs whose resistance are in the ratio 1:2, are connected in parallel to a source of

constant voltage. What will be the ratio of power dissipation of these?21.Two wires, one of manganin and the other of copper have equal length and resistances.

Which one of these wires will be thicker?22.Two wires A and B are of the same metal, have the same area of cross-section and have their

lengths in the ratio of 2:1. What will be the ratio of currents flowing through them respectively when the same potential difference is applied across length of each of them?

23.How much current will an electric heater rated 1 kW draw when connected to 250 V?24.A students obtains resistance of 3,4,12 and 16Ώ using only two metallic resistance wires are

either separately or joined together. What is the value of resistance of each of these wires?25.An electric iron has a rating of 750 W, 220 V. Calculate

(i) Current passing through it, and(ii) Its resistance, when in use.

26. An electric iron has a rating of 1000 W , 220 V. when in use calculate for it (i) Current passing through it,(ii) Its resistance.

27. An immersion heater has a rating of 2 kW, 220 V. while in use calculate(i) Current passing through it,(ii) Its resistance.

28 An electric lamp is marked 100 W, 220 V. it is used for 5 hours daily . Calculate(i) Its resistance while glowing.(ii) Energy consumed in kWh per day.

29 An electric lamp is marked 40 W ,220 V. It is used for 4 hours daily. Calculate(i) Its resistance while glowing.(ii) Energy consumed in kWh per day.

30 An electric lamp is marked 25 W ,220 V. It is used for 4 hours daily. Calculate(i) Its resistance while glowing.(ii) Energy consumed in kWh per day.


SARASWATI STUDY POINT 31 (i) Draw a diagram to show how two resistors R1 and R2are connected in series. (ii)In a circuit of two resistors 5 ohm and 10 ohm are connected in series, how does the

current passing through the two resistors compare? 32 A bulb is rated at 5.0 volt, 100 mA. Calculate its (i) power and (ii) resistance. 33 What is the difference between direct and alternating currents? Write one important advantage

of using alternating current. 34 A trouch bulb is rated 3 V and 600 mA. Calculate its resistance if it is lighted for 4 hours. 35 An electric bulb draws a current of0.2 A when the voltage is 220 volts. Calculate the amount of

electric charge flowing through it in one hour. 36 Calculate the amount of charge that would flow in 1 hour through the element of an electric

bulb drawing a current of 0.2 A. 37 State Ohm’s law. Express it mathematically. Define S.I. unit of resistance. 38 Define the term resistivity of a conductor. Give its S.I. unit. 39 Define resistivity and state its S.I. unit. Does it vary with temperature? 40 A heater coil is rated 100 W, 200 V. it is cut into two identical parts. Both parts are connected

together in parallel to the same source of 200 V. Calculate the energy liberated per second in the new combination.

41 In varying temperature conditions, why Ohm’s law does not hold good? 42 Why is the loss of energy in a circuit due to the use of an ideal ammeter and an ideal volmeter,

zero? 43 If P = V2/R holds good, does power of bulb depend on V. why ? 44 How does a rheostat vary the resistance in a circuit? 45 A wire of length l, area A is made into a wire of double its length by (i) attaching s similar

wire (ii) melting the existing wire? If the original resistivity is p, what will be the new resistivity and resistance?

46 Find the equivalent resistance in the following circuits.

47 A circuit having twenty similar bulbs connected in series is applied a potential V0.(i) If 5 of the bulbs (randomly) gets fused and the rest are connected in series to the same supply, will

the power consumed increase or decrease. Why?(ii) When will there be a chance that the rest of the 15 bulbs will get fused or not glow.

48 A bulb of 40 W, 220V is supplied 220 volt potential. A 2 A fuse is saving it. If a 1500 W, 220 V motor is connected in parallel to the bulb, how much excess current will flow through the fuse? Will the bulb glow?

49 How many kWh’s make 1 joule? 50 A hot plate of an electric oven connected to a 220 volt lines has two resistance coils A and B,

each of 24 Ώ resistance which may be used separately, in series or in parallel.(i) What will be the power consumed in each case?


SARASWATI STUDY POINT(ii) In each of the two cases, find the rating of the fuse required?(iii) In which case, time consumed to heat 5 litres of water more?

51 How can you make 3Ώ by using 2Ώ resistors available with you? 52 Four cells of 2 V each are connected in series with a 5Ώ resistor. If by mistake 2 cells are

connected wrongly (polarities changed) what will be the change in current in 5Ώ resistor?

53 Two resistors and their series combination are shown graphically.

(i) Identity the resistors from the given I-V graph(ii) Which one represents the series combination of the other two? Given reason for your answer (iii) Which resistor has the more value than the other?(iv) Plot the V-I graph for the same.

54 In the adjoining figure A,B and C are three ammeters. The ammeter B reads 0.5 A. (All the ammeters have negligible resistance)

Calculate(i) The reading of the ammeters A and C.(ii) Potential difference measured by the voltmeter across 6Ώ(iii) The total resistance of the circuit.

55 A wire is connected between the points X and Y in the circuits to carry a current I. if it is replaced by a wire of(i) Same length and half thikness(ii) Half length and same thikness, how will the current vary?

56 Two wires A and B of same length made of the same material have their V-I graph, as shown. Which of them is thiker?

57 Four resistance 2.0 Ώ each are joined end to end form a square ABCD. Calculate the equivalent resistance of the combination between:(i) Any two adjacent corners. (ii) Any two opposite corners.(i) Combination of L3 and L4 are same or different. Why?


SARASWATI STUDY POINT(ii) The reading of voltmeter across bulb L2 is 10 V. calculate the power being transferred by the bulb

58 A Resistance of 6 ohms is connected in series with another resistance of 4 ohms. A potential difference of 20 volts is applied across the combination. Calculate the current through the circuit and the potential difference across 6 ohms resistance.

59 Three resistance of 4Ω, 6Ω and 10Ω are connected in series. The potential difference across the combination is 5v. Calculate the potential difference across each resistor.

60 In the circuit shown, the potential difference across the 4Ω resistor is 8v.(i) What is the current through the 4Ω resistor?(ii) What is the current through the 3Ω resistor?(iii) What is the potential difference across the 3Ω resistor?(iv) What is the potential difference applied by the battery?

61 In the diagram given alongside, the potential difference across PR is 14 volts. Calculate.(i) Te equivalent resistance of the network QR,(ii) The current flowing through PQ,(iii) The potential difference across PQ,(iv) The current flowing through the 3 ohm resistor.

62 A pupil made an electric circuit like the one shown alongside in order to measure the current through the (i) Are the two lamps in series or in parallel?(ii) The pupil has made a mistake in this circuit what is

the mistake?(iii) Draw a diagram showing the correct way to connect

this circuit. Use the proper circuit symbols in your diagram. 63 For a circuit given alongside. find;

(i) Total resistance of the circuit (ii) Total current flowing though the circuit(iii)Potential difference across 7.2 ohm resistor.

64 (a) Two conductors A and B of resistance 5Ω and 10Ω respectively are arranged in parallel and later in series. In each arrangement the total voltage across it is 20 volts. In which arrangement will the voltage across A and B be the same and in which case will the current flowing through A and B be the same?(b) Calculate the total resistance for each arrangement.

65 A wire bent in the form a circle has resistance of 40Ω A and B are the two points on the wire dividing it into a quadrant. Find the values of l1 and l2

66 The voltage of a battery is 10v. Find the amount of work done to transfer a charge of 20 C from one terminal to the other?

67 A bulb is rated at 200 V, and 100 W. What is its resistance? Five such bulbs are lit for 4 hours. How much electrical energy is consumed? Calculate the cost if the rate is 50 paisa per unit.


SARASWATI STUDY POINT68 An electric Kettle rated at 220 V, 2.2 KW, works for 3 hours. Find the energy consumed and the

current drawn. 69 A bulb is rated at 220 V, 200 W. What is its resistance?70 A radio set of 60 W runs for 50 hours. How much electrical energy is consumed?71. A current of 5 A flows through an electric heater which is connected to a voltage of 250V. Find

the amount of heat produced in 10 minutes. 72. Two electric bulbs of 100 W each are used for 8 hours daily. Find the cost of using them for 1

day is 75 paise per unit. 73 Two resistance of 20Ω and 40Ω are connected in series to a battery of potential difference 10

Volt. Compare the ratio of the heat produced in one minute in the two resistances.74 A resistance of 40 ohms and one of 60 ohms are arranged in series across a 200 V battery. Find

the heat in calories produced by this combination in ½ minute.75 In which of the following cases is more electrical energy consumed per hour.

(a) A current of 1 A is passed through a resistance of 300 ohms?(b) A current of 2 A is passed through a resistance of 100 ohms?

76 Two electric lamps rated 100 W, 220 V and 25 W, 220 V are connected in parallel to a 220V supply. Calculate the total electric current in the circuit.

77. A metallic coil connected to a 220V supply, has a resistance of 110 ohms (while hot) How long will it take this coil to heat 1Kg of water from 20°C to 70°C? Assume that whole of heat produced by the coil is taken up by water.

78 State the formula correlating the electric current flowing in a conductor and the voltage applied across it. Also show this relationship by drawing a diagram. What would be the resistance of a conductor if the current flowing through it is 0.35 ampere when the potential difference across it is 1.4 volt?

79 (a) State the formula showing how the current l in a conductor varies when the potential difference V applied across it is increased stepwise.(b) Show this relationship also on a schematic graph. (c) When a potential difference of 1.2 volt is applied across a conductor the current flowing in it is 0.25 ampere. Calculate the resistance of the conductor?

80 (a) Express ohm’s law both by a mathematical formula and by a graph line.(b) State SI unit of (i) resistance and (ii) resistivity.(c) What will be the equivalent resistance R of two resistors R1 and R2 (i) connected in series

and (ii) connected in parallel.81 (a) Express ohm’s law by a mathematical formula.

(b) Draw a circuit diagram to verify ohm’s law.(c) Present the relationship between the voltage applied across a conductor and the current following through it graphically.

82 A cylinder of a material is 10 cm long and has a cross-section of 2 cm2. If its resistance along the length be 20 ohms, what will its resistivity value be in number and units?


SARASWATI STUDY POINT83 Define resistivity of a material.84 A torch bulb is rated 2.5V and 750 mA. Calculate (i) its power, (ii) its resistance and (iii) the

energy consumed if this bulb is lighted for 4 hours.85 Why is much less he4at generated in long electric cables than in filaments of electric bulb?86 What is the power of a torch bulb rated at 25V and 500 mA?87 Two electric lamps of 100W and 25W, respectively are connected in parallel to a supply voltage

of 200V. Calculate total current flowing through the circuit.


SARASWATI STUDY POINTMagnetic Effects of Electric Current

MAGNETIC FIELD AND MAGNETIC FIELD : - The space around magnets in which the force of attraction and repulsion due to the magnet can be detected is called the magnetic field. The curved paths along which the iron filings arrange themselves due to the bar magnet are called magnetic field lines.CHARACTERISTICS OF MAGNETIC FIELD LINES:-

(i) The field lines come out of the North pole and get into the South pole (closed loops are formed).

(ii)The strength of magnetic field is indicated by the closeness of the field lines. Closer the lies, more will be the strength and farther the lines, lesser will be the field strength.

(iii)No two field lines will intersect each other if they interested there will be tow different directions for field at the same point which is not possible.

NOTES: - Magnetic field is a vector quantity The direction of the magnetic field is taken to be the direction in which a north pole of the

compares needle moves inside it. Therefore it is taken by conversion that the field lines emerge from North Pole and merge at the South pole.

Inside the magnet, the direction of field lines is from its south pole to its north pole. Thus, magnetic field lines are closed curves.

The relative strength of the magnetic field is shown by the degree of closeness of the field lines. The field is strength, that is the force acting on the pole of another magnet placed is greater where the field lines are crowded.

MAGNETIC FIELD DVE TO A CURRENT-CARRYING CONDUCTOR: - Connect the circuit with one cell initially

Place the straight wire parallel to and over the compass needle. Observe the deflection of needle while pressing the key. Reverse the current by interchanging the connections of terminals of the cell. Increase the strength of current by increasing the number terminals in the circuit and

observe the angle of the needle each time.OBSERVATION:-

The direction of magnetic field depends on direction of current which can easily find out by “SNOW” rule.

B x I (Here B is magnetic field and I, r are current and radiusB x 1/r of magnetic field line respectively.

RIGHT HAND THUMB RULE:- Hold the wire carrying current in your right hand, such that the thumb indicates the direction of current, then the folded fingers will indicate the presence of magnetic field (lines) surrounding the wire.


SARASWATI STUDY POINTMAGNETIC FIELD DUE TO A CURRENT CARRYING CIRULAR WIRE: - Coil is given by the fig.The direction of field is perpendicular to the coil and directed inwards for the clock wise current flowing. For anticlockwise current, it will be flowing anticlockwise. The field lines in circular coil have the following character: (i) Circular near the wire.

(i) Straight at the centre(ii)Field is perpendicular to the plane of the coil(iii)For larger areas, the field at the centre is uniform.

MAGNETIC FIELD DUE TO CURRENT-CARRYING SOLENOID: - An insulated copper wire wound on a cylindrical cardboard tube such that its length is greater than its diameter is called a solenoid. The solenoid is from Greek work for channel.

The magnetic filed inside a solenoid is uniform. A current-carrying solenoid behaves like a bar magnet with fixed polarities at its ends. B x

I, B x N, B x 1/r.

ELECTROMAGNETS AND PERMANEDIT MAGNETS: -

ELECTROMAGNETS:- An electromagnet is a temporary strong magnet and is just a solenoid with its winding on a soft iron core. The strength of the electro magnet depends upon: B x I, B x N

Electromagnets are used in electrical devices such as an electric bell, an electric far, telegraph an electric train, an electric motor generator etc.

PERMANENT MAGNET: - A permanent magnet is made from steel. As steel has more retentively than iron, it does not lose its magnet6ism easily.

Apart from different varieties of steel, some alloys like alnico and Nipermag are used to make very strong permanent magnets.

ELECTROMAGNET PERMANENT MAGNETI. An electromagnet is a temporary I. A permanent magnet cannot readily magnet as it can readily be demagnetized. demagnetized by stopping the current through the solenoid. II. An electromagnet produces a II. The magnetic field of a permanent

strong magnetic field whose magnet is comparatively weak strength can be changed by and its strength cannot be change changing the current through

the solenoid.III. The polarity of an electromagnet III. The polarity of a permanent magnet Can easily be reversed by changing is fixed and cannot be easily

the direction of current through reversed. the solenoid.


SARASWATI STUDY POINTFORCE ACTING ON A CURRENT-CARRYING CONDUTOR IN A MAGNETIC FIELD: When a current-carrying conductor is placed in a magnetic field, it experiences a force, except when it is placed parallel to the magnetic field.

FLEMING LEFT-HAND RULE:- Stretch the thumb, the first finger and the central finger of the left hand so that they are mutually perpendicular to each other. If the first finger points in the direction of the magnetic field, the central finger points in the direction of current, then the thumb point in the direction of motion of the conductor.

ELECTROMAGNETIC INDUCTION: - the phenomenon of generation of an electric current a circuit from magnetic effects, by changing the magnetic flux linked with it is called electromagnetic induction.

ELEMING’ RIGHT –HAND RULE: - Stretch the thumb the first finger and the central finger of the right hand so that they are mutually perpendicular to each other. If the first finger points in the direction of magnetic field, the thumb points in the direction of motion of the conductor, then the central finger points in the direction of induced current.‘An electric current which changes its direction after a certain fixed interyal of time is called alternating current. An electric current which always flows in the same direction is called direct current. ADVANTAGES OF AC OVER DC: - The we stage in AC transmission is almost negligible and as such the cost of transmission is low.

HOUSE-HOLD CONNECTION: - We use parallel connection in various electrical points in the house. This is because; (i) Individual appliance can be operated at any time (ii) All appliances will get the same potential difference of 220 volts, needed for their operation.

Domestic Electric Circuits: - The electric power in our homes is supplied at 220v, 60H2. The main component of domestic electric circuits are (i) Live or positive wire-covered with red insulation (ii) Neutral or negative wire-covered with black insulation. (Earth wire- covered with green insulation.

EARTHING OR EARTH WIRE: - the earth wire is usually connected to a copper plate in the earth near the house. The metallic body of the entire electrical appliance is connected to earth wire. The earth wire provides a low resistance to the current hence any leakage of current to the metallic body keep its potential equal to that of the earth , zero potential and the user may not get a serve electric shock . Earth wire is connected in parallel with domestic circuits.


SARASWATI STUDY POINTOVERLOADING; - if the total current drawn by all the appliances at a particular time exceeds the bearing capacity of that wire, the wires of the domestic wiring get heated. This is known as overloading. It might be due to (i) accident rise in supply voltage. (ii) Connecting many devices to one socket.

FUSE-WIRE: - it is a safety wire connected in series in the live wire. In case of any large current supply or malfunctioning in the electric connections, joules heating effect takes places, the fuse wire melts and disconnects the entire circuit from the electrical supply. The fuse wire should have. (i) High resistance, high resistively and (ii) low melting point. Normally, the fuse wire is made of an alloy of copper and tin. (ii)ADVANTAGE OF FUSE WIRE: - it protects the circuit and appliances by stopping the flow of any large electric current-May even be caused by overloading.

Questions1. How will the magnetic field change when the distance from the current carrying conductor is

increased?2. State right hand thumb rule.3. What is a solenoid?4. What is the direction of magnetic field lines outside a bar magnet?5. Why does a compass needle get deflected when brought near a metallic wire current? Who

invented the effect?6. What is the use of inserting a soft iron core inside a current carrying solenoid?7. What is the value of magnetic field inside a long straight solenoid carrying current?8. A straight metallic wire carrying current is bent in the form of a circle, how does the magnetic

field get affected at a particular point.9. What is the S.I unit of magnetic field?10. What does crowding of magnetic field lines indicate?11. In which direction the magnetic needle moves when placed over current carrying conductor. If

the current flows from North to South.12. How does magnetic field change inside a long straight solenoid carrying current.13. What type of current is used in household supply?14. Name the magnet produced on inserting a soft iron core inside a current carrying solenoid.15. What type of current is given by a cell?16. Name a device based of principle of electromagnetic induction.17. A current carrying conductor is placed perpendicular to magnetic field. In which direction does

the conductor experience a force?18. What is the frequency of domestic AC supply in India?19. To which wire do you connect fuse wire in household electricity?20. What is Fleming’s right hand rule?21. Indicate the colours of neutral & live wire.


SARASWATI STUDY POINT22. What does arrow of magnetic field line indicate?23. A current in horizontal power line is from east to west. What is the direction of magnetic field

at a point directly (i) Below it (ii) Above it?24. What are the various methods of Induce electric in the coil?25. What is the pattern of the magnetic field at the centre, near portion of circular coil?26. How do we connect earth wire in a house?27. State the principle of electric motor.28. Give one example of the use of (i) Permanent magnet (ii) Electromagnet.29. State the principle of Dynamo.30. Name the device used in head lights of scooter? On what principle does it work?31. Draw a labeled diagram of electric motor.32. What is an armature? What is the use of split lights?33. How will the magnetic field produced in a current carrying a circular coil change if we (i)

Increase the value of current (ii) Increase the distance from the coil. (iii) Increase the no. of turns of coil.34. Draw labelled diagram of Dynamo.35. What is the colour used in insulation of earth wire? What is the use of earth wire?36. Write principle, construction & working of AC generator?37. Write principle, construction & working of electric motor.


SARASWATI STUDY POINTSources of Energy

Important terms and definitions

Sources of Energy: - Any system from where energy can be tapped is called a source of energy.

Characteristics of Source of Energy:-(i) Capable of providing adequate amount of energy.(ii) Should be convenient to use and easy to store and transport.(iii) Should be capable of giving desired quantity at required rate steadily over a long period.(iv) Should release energy in mostly all forms in which the day-to-day requirement exists.

Fossil Fuel: - The fuels which are obtained from the remains of plants and animals are called fossil fuels, e.g., coal, petroleum and natural gas.

The remains of plants and animals which got buried inside the earth million of years ago, changed into coal, petroleum and natural gas due to excess of heat and high pressure inside the earth. These conditions do not exist anymore, so new reserves of these fuels are not being formed now.

Disadvantages of using fossil fuels:-(i) Burning of coal and petroleum lead to air pollution.(ii)They cause acid rain by forming acidic oxides of Carbon, Nitrogen and Sulphur.

However, it can be reduced by the use efficient combustion process and techniques to reduce gases and ashes dropped in the surrounding.

Thermal Power Plant: - In power stations, one needs energy to run turbines. Large quantity of fossil fuels like coal is burnt to produce heat energy. This produces steam which is used to rotate turbines to produce electricity. The flow of energy is listed below:Fossil fuels – Heat Energy – Mechanical Energy – Electrical Energy.

Hydroelectricity: - The energy of water flowing through rivers or stored in dam is another potential source of energy. It is also indirect source of solar energy. It is the solar energy which recycles water in nature from oceans and the earth’s surface through rain and snow. The energy of water flowing through rivers has been used for rotating the wheels of watermills which are still operating in remote hilly areas.

Generation of Hydroelectricity: - The water flowing in river is collected in the dam which is allowed to fall from the top of dam. Water turbine is located near the bottom of the dam and the shaft of water turbine is connected to electric generator. When fast moving water coming from the dam falls on the blades of water-turbine, then kinetic energy of water rotates the water


SARASWATI STUDY POINTturbine rapidly. When the water-turbine rotates, then the armature (coil) of generator also rotates rapidly and generates electricity. In generation of hydroelectricity, potential energy of stored water is converted into kinetic energy of flowing water which is converted into electrical energy using turbine.Bhakra Nangal Dam is being used to produce electricity.

Advantages of Hydroelectricity:-(i) It does not create pollution.(ii)Water energy is renewable source of energy which will never get exhausted.

Disadvantages of Hydroelectricity:-(i) The construction of dams may lead to ecological imbalances.(ii)A vast variety of animals, plants get submerged in water.(iii) It decreases fertility of soil on down-stream area and affects crops.(iv) Creates problem of satisfactory rehabilitation

(e.g., Tehri dam – Sardar Sarovar project on Narmada)(v)Rotten submerged vegetation produces greenhouse gases.

Biomass: - The material contained in the bodies of plants and animals is called biomass. It acts as a fuel. It includes wastes from tree and grass crops forestry agricultural and urban wastes. The excreta of living organisms and their bodies after death also continue to the biomass.

Biogas: - It is a mixture of gases such as methane (75%), carbon dioxide, hydrogen, hydrogen sulphide, etc. which is obtained by the decomposition of animal and plant wastes like animal dung, etc. with the help of micro-organisms in the presence of water. It is used as fuel in gas-stoves these days especially in rural areas. It can be used for street lighting and for running engines.

Production of Biogas: - Biogas is a mixture of gases produced during decay of biomass in the absence of oxygen. Methane is main constituent of biogas, which is an excellent fuel.Animal dung, sewage, crop residues, vegetable wastes, poultry droppings, wastes from agrobased industries are some forms of biomass that are most suitable to produce biogas.Metal pieces, plastic, polythene, glass pieces, paper are not suitable for production of biogas. Biogas technologies are gaining acceptance sustaining source of fuel and electricity by both rural and urban population. There are two designs of commonly used Biogas plants – (i) Fixed dome type (ii) Floating gas holder type.

Fixed Dome type Biogas Plant:-Construction:(i) It consists of well shaped underground tank (called digester) covered with dome-shaped

roof, both made of bricks and cement.


SARASWATI STUDY POINT(ii) The dome of the digester is fixed so that it acts as gas holder (or gas storage tank) for

the biogas produced. (iii)At the top of dome, there is a gas outlet pipe and a gas valve.(iv) There is sloping inlet chamber called mixing tank on the left side of the digester and on

the right side, there is a rectangular outlet chamber, both made up of bricks and cement.(v) Fresh cattle dung and water form slurry which is introduced in the inlet chamber while

the spent dung slurry gets collected in the outlet chamber. The inlet chamber is connected to the mixing tank; while the outlet chamber is connected to the overflow tank.

Fixed Dome type biogas plantWorking:-

(i) Slurry (made by mixing equal proportions of animal dung and water) is fed into digester tank via the inlet chamber, till the slurry level becomes nearly equal to the cylindrical top level.

(ii) The biogas plant starts functioning in about 50–60 days. During this time, cattle dung undergoes fermentation in the presence of anaerobic bacteria with gradual evolution of biogas, which starts collecting in dome shaped space.

(iii)As the time passes, more and more biogas collects inside the dome, thereby exerting pressure on the slurry in the digester tank and this in turn forces the spent slurry to the overflow tank via outlet chamber.

(iv) The spent slurry is withdrawn periodically and used as good manure because it is rich in essential plant nutrient.

(v) Fresh slurry is added to the mixing tank and fed digester for the regular supply of biogas.

(vi) The biogas collected in the dome is taken out through the outlet pipe by opening the gas valve and then used as fuel gas.

(vii) Fixed dome type biogas plant is also called Janta gobar gas plant.

Advantages of Fixed Dome type Biogas Plant: -(i) It is quite cheap, since it is made up of cement and bricks.(ii) There is less cost on the maintenance.(iii) It has longer life and they can make use of human excreta and other biowastes.PITAM PURA & ROHINI (www.saraswatichemistrypoint.com) 011-27316087 / 9899899326 48

SARASWATI STUDY POINT(iv) There is no problem of corrosion or rusting.

Uses of Biogas:- (i) It is used as fuel for domestic purposes.(ii) It is used as fuel to run engines.(iii) It is used as illuminant in villages.

Solar Cooker: - A Solar Cooker is a device which is used to cook food using solar energy. It consists of an insulated metal box or wooden box, which is painted all black from inside. There is a thick glass cover, glass sheet as a cover over the box and a plane mirror which acts as reflector attached to the box. The food to be cooked is placed in a metal container and the black painted container is kept in box and covered with glass sheet. Solar Cooker is kept in sunlight in such a way that strong beam of sunlight falls over the cooker top. The sun rays pass through the glass sheet cover and get absorbed by black surface and temperature in the box slowly rises up and reaches 100C to 140C by infrared rays. The heat cooks the food.

Box Type Solar Cooker Limitations of Solar Cooker:-

(i) It cannot be used during night time.(ii) It cannot be used on cloudy day.(iii)The direction of reflector of solar cooker has to be adjusted frequently.(iv) It cannot be used for frying.(v) It cannot be used for making chapaties.(vi) It takes longer time for cooking.

Advantages of Solar cooker:-(i) It saves fuel.(ii) It does not create pollution.(iii)The nutrients of food do not get destroyed.

Solar Cells: - It is a device which converts solar energy, i.e., light energy directly into electricity. They are made up of semiconductors like silicon, germanium and selenium.

How solar cells are made? Solar cells are made up of silicon and gallium. In solar cell, the pieces (usually wafers) of semiconducting materials containing impurities are so fused that a potential


SARASWATI STUDY POINTdifference develops between the two regions of semiconductors when light falls on it. The current produced by single cell measuring about 4 cm2 may be of the order of 0.4 to 0.5 V at 6.0 mA (milliampere).

Solar Cell Panel: - It comprises of a large number of solar cells and can provide higher power for many uses.

Uses of Solar Cells: -(i) All artificial satellites and space probes mainly depend upon electricity generated by solar

cells.(ii) In India, solar cells are used for lighting, operating water pumps, for running radio and

television sets in remote areas and traffic signals etc.(iii)They are being used to provide electric power to light houses and off shore drilling rig

platforms.(iv) Solar cells are used for calculators and electronic watches.

Advantages:-(i) Immobile so less maintenance.(ii) Can be made available even in areas inaccessible to other energy means.

Windmill: - The windmill works on the principle, that, when the blowing wind strikes across the blades of a windmill it exerts a force which rotates its blades. The rotational effect is due to a special design of the blades similar to those of an electric fan, the windmill may be considered as an electric fan working in the reverse order in which blowing air rotates the blades of the windmill.

Advantages:-(i) Involves no recurring expenditure.(ii)Eco-friendly and efficient.

Disadvantages:-(i) Needs large open field.(ii) Initial cost is very high.(iii) Needs higher level of maintenance.(iv) Not available at all times and at all places.

Windmill to pump out water from a well or flooded coal mine

Energy from Oceans: - It is a potential source of renewable energy. There are many forms of ocean energy.(i) Ocean Thermal Energy (OTE). There is always a temperature difference between water

at the surface and at deeper level up to 20C. This form of energy is called ocean thermal energy which can be converted into electricity.


SARASWATI STUDY POINT(ii) Sea-Waves Energy: - Energy from oceans is also available in form of sea-waves. Due to

blowing of wind on the surface of ocean, very fast sea-waves move on its surface. It has a lot of kinetic energy due to high speed. It can be used to produce electricity. Some specially designed devices are set up in the sea which moves as the sea-waves pass them. Their movement can be used to drive dynamos which generate electricity.

(iii)Tidal Energy: - The rise of ocean water due to attraction of moon is called ‘high tides’ whereas fall of ocean water is called ‘low tides’. The tidal waves rise and fall twice a day. The enormous movement of water between ‘high tides’ and ‘low tides’ provides a very large source of energy in the coastal areas of the world. Tidal energy can be harnessed by constructing a tidal barrage or tidal dam. The sea water risen during high tide trapped by the barrage is allowed to fall down on water turbines due to which they start rotating. The rotating water turbines drive generators which produce electricity.

Geothermal Energy: - The heat from inside the earth heats up the water below the surface. This hot water can be used under favourable conditions as a source of energy. This energy with hot water below the earth is called geothermal energy. Underground water gets converted into steam and remains trapped between rocks at high pressure. The steam taken out at high pressure can run turbine to generate electricity. In some places without any drilling, hot water with steam comes out. They are called as hot springs or geysers.

Advantages: -

(i) Available all the time.(ii) It is clean.(iii) It is environment friendly. (iv) It is cost effective when converted to electricity.

Hot springs are seen at three places in India, but none of them is of use to us on commercial basis. The three places are in (i) Madhya Pradesh, (ii) At Sohna, Gurgaon district of Haryana and (iii) At Manikaran, Kullu district of Himachal Pradesh.New Zealand and USA are two major areas where commercial use of geothermal energy is done.


SARASWATI STUDY POINTQuestions

1. What is acid rain?2. What is Bio-mass?3. What is the law of conservation of energy?4. What is the principle of turbine?5. Thermal power plants are set up near coal or oil fields. Why?6. What is the slurry? Which gases are produced after its decomposition?7. What is the major fuel used to generate electricity?8. What is green house effect?9. What is the principle of dynamo?10. What is the main gas present in Bio-gas?11. What is wave energy?12. Name a material used in making of solar cell?13. What is the principle of hydro thermal power plant?14. What is the various limitation of solar cell?15. Why do we blackened the outer surface of solar-cooker?16. What is the use of slurry? Which gases are produced after its decomposition by anaerobic

microorganisms?17. What is the range of voltage & power which can be developed by typical solar cell?18. How many times energy released during nuclear fission is more than energy released from coal?19. What is the main source of energy in artificial satellite & space probes?20. Out of C.N.G and hydrogen, which gas is cleaner? What is the full form of C.N.G?21. Name a material used for interconnecting solar cells for making solar-panel.22. What are the advantages of Bio-gas?23. What is tidal energy?24. What are hot-springs? What is their use?25. What is the good source of energy?26. What are non-renewable sources of energy? Give two examples.27. What are the limitations of wind energy?28. What are the various energy potential from the sea?29. What kind of mirror one should use in solar cooker & why?30. What are renewable source of energy? Give two examples.31. What are the advantages of solar cells?32. What are the advantages of using wind energy?33. Name two dams having strong opposition for their construction.34. What is the main gas present in Bio-gas?35. What are disadvantages of burning fossil fuel?36. What are the various problems in constructing dams to generate electricity?37. What is bio-gas? Explain working of bio-gas plant with the help of diagram.38. With the help of diagram, explain the working of hydropower plant.


Chemical Reactions & Equations - Saraswati Chemistry · Web viewHow are mineral transport in plant...

Documents

Transcript of Chemical Reactions & Equations - Saraswati Chemistry · Web viewHow are mineral transport in plant...