10th CBSE{SA I} Pioneer Education - · PDF file · 2013-09-05Pioneer Education...

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10th CBSE{SA – I}

Science

Solution of Mock Paper With

Blue Print of Original Paper on Latest Pattern

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General Instructions:

Time: 3hrs. M: M: 90

(i) The question paper comprises of two sections, A and B, you are to attempt

both the sections.

(ii) All questions are compulsory.

(iii) There is no overall choice. However, internal choice has been provided in all the

three questions of five marks category. Only one option in each question is to be

attempted.

(iv) All questions of Section A and all questions of Section B are to be attempted

separately.

(v) Question numbers 1 to 3 in Section A are one mark questions. These are to be

answered in one word or one sentence.

(vi) Question numbers 4 to 7 are two marks questions, to be answered in about

30 words.

(vii) Question numbers 8 to 19 are three marks questions, to be answered in

about 50 words

(viii) Question numbers 20 to 24 are five marks questions, to be answered in

about 70 words

(ix) Question numbers 25 to 42 in Section B are multiple choice questions based

on practical skills. Each question is a one mark question. You are to choose one

most appropriate response out of the four provided to you.

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10th CBSE

First Term {SA- I}

Blue Print

Total Marks: 90

MCQ : 18

Theory : 72

Form of Questions/Unit VSA SA (I) SA (II) LA MCQ Total

1. Chemical

Substances

(i) Chem. Reactions &

Equations

(ii) Acids, Bases& Salts

(iii) Metals and

non- metals

1(1)

-

2(1)

-

6(2)

6(2)

3(1)

-

5(1)

5(1)

1(1)

3(3)

1(1)

2. Effects of

currents

(i) Electricity

(ii) Magnetic effects of

current

1(1)

-

2(1)

2(1)

9(3)

3(1)

-

5(1)

7(7)

-

3. World of Living

(i) Life processes

(ii) Control and

coordination

-

-

2(1)

-

-

3(1)

5(1)

5(1)

6(6)

-

4. Natural Resources

Sources of energy 1(1) - 6(2) - - 7(3)

Total 3(3) 8(4) 36(12) 25(5) 18(18) 90(42)

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Weightage of questions

S.No. Form of Question Marks for each question No. of questions Total Marks

1. VSA 1 3 3

2. SA (I) 2 4 8

3. SA (II) 3 12 36

4. LA 5 5 25

24 72

MCQ 1 18 18

Grand Total 90

Distribution Chapter wise

S.No. Content Marks (Theory)

MCQ Total

1.

Chemical Substance

(i) Chem, Reactions &

Equations

(ii) Acids, Bases & Salts

(iii) Metals, and non-metals

9

11 28

8

5 33

2.

Effects of current

(i) Electricity

(ii)Magnetic effects of current

1222

10

7 29

3.

World of living

(i) Life processes

(ii) Control and coordination

715

8

6 21

4. Natural resources

Sources of energy 7 - 7

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Section – A

1. What does the direction of thumb indicate in the right-hand thumb rule ?

Sol :

The direction of thumb indicates the direction of flow of current through a straight conductor

in right-hand thumb rule.

2. On what basis is a chemical equation balanced?

Sol :

Chemical equations are balanced on the basic of law of conservation of mass. According to

which total mass of reactants is equal to the total mass of products during any chemical

change.

3. Name the plant hormones responsible for elongation of cells.

Sol:

Auxin and cytokinin are responsible for elongation of cells.

4. For making cake, baking powder is taken. If at home your mother uses baking soda instead of

baking powder in cake,

(a) how will it affect the taste of the cake and why?

(b) how can baking soda be converted into baking powder?

Sol :

(a) The cake will taste bitter as tartaric acid has not been added to baking soda (i.e. Baking

powder was not used) to neutralize the effect of the mild basic salt i.e. baking powder.

(b) Baking Soda can be converted into baking powder by adding tartaric acid to it.

5. In one of the industrial processes used for manufacture of sodium hydroxide, a gas X is

formed as by product. The gas X reacts with dry slaked lime to give a compound Y which is

used as a bleaching agent in chemical industry. Identify X and Y.

Sol :

The gas X is Cl2 (chlorine gas). The substance Y used for bleaching is bleaching powder.

(CaOCl2).

n2 22

Rex Ca OH Cl CaOCl

6. What are the constituents of solder alloy? Which property of solder makes it suitable for

welding electrical wires?

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Sol :

Solder alloy is formed by a homogeneous mixture of 50% lead (Pb) and 50% Tin (Sn). Solder

has a low melting point and high resistivity. Solder is used for welding electric wires so as to

prevent them from short circuiting .

7. A battery of 9 V is connected in series with resistors of 0.2 , 0.3 , 0.4 , 0.5 and 12

resistors. How much current would flow through the 12 resistor ?

Sol :

Potential different across terminals of battery (v) = qV

Total resistance, Rs = (.2+ .3 + .4 + .5 + 12)

= 13.4

As, in series combination current (I) is constant through all resistors, current through 12

resistance = current through the circuit, I = V

R

= 9

13.4

= 90

134

= 0.67 A

Therefore correct through 12 resistor is 0.67 A as current in series combination is same.

8. A student constructed a model of box type solar cooker. He used a transparent plastic sheet to

cover the open face of the box. He found that this cooker does not function well. What could be

the possible drawbacks in his model ? List any four drawbacks.

Sol :

He may not have used :

(i) black painted aluminium sheet

(ii) black cooking vessel to absorb heat radiation.

(iii) glass sheet, which prevents the escape of heat radiation from the box instead of plastic

sheet.

(iv) mirror plate which reflects the sunlight to fall on the glass sheet.

9. A copper wire has a diameter of 0.5 mm and a resistivity of 1.6 × 10–8 ohm m. What will be the

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length of this wire to make its resistance 10 ohm? How much does its resistance change if the

diameter is doubled?

Sol :

R 10

d = 0.5 mm

r = 0.25 mm = 0.25 × 10–3

= 1.6 × 10–8 m

length, l = ?

RAl

P

= 6

8

10 3.14 0.0625 10

1.6 10

= 33.14 0.0625 10

1.6

= 314 0.625

1.6

= 314 6.25

16

= 314 625

16 100

= 314 25 25 25 25

4 4 4 25 25 25

= 6

314 625 625

10

= 6

390625 314

10

= 122.65625 m

10. How do the guard cells regulate opening and closing of stomatal pores?

Sol :

Guard cells regulate the opening & closing of stomatal pores. When water enters into guard

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cell, due to difference in water concentration gradient, they swell up and stomatal pores open.

This is because inner linning of guard cells is thicker and outer membrane is thin due to which

they buldge outwards. When this water moves out of guard cells, they shrink and get flattened

leading to closing of stomatal pore.

11. "All plants give out oxygen during day and carbon dioxide during night". Do you agree with

this statement? Give reason.

Sol :

Yes this time, as during the day sunlight being present, they have to make food and for this

they give out oxygen and take in CO2 (Carbon dioxide) but during night they don’t perform

photosynthesis and hence release CO2 and take in O2 (oxygen for respiration).

Although respiration takes place during the day also but the amount of O2 released during

photosynthesis is much more than O2 consumed in the process of respiration.

12. What happens at the synapse between two neurons?

Sol :

At the synapse between two neurons, information is transferred from the axon endings of one

neuron to the dendrites of next neuron in the form of chemical impulse. In short, transfer of

information between two neurons takes place at the synapse.

13. Explain how does current flow in a conductor.

Sol :

A conductor contains a large number of free electrons which are always in random motion.

When a potential random motion. When a potential difference is maintained across such a

conductor using a battery the electrons drift towards the positive potential of the battery and

will now have a fixed direction. This causes an electric current. All the free electrons are

moving in the same direction with the same speed.

14. Write one equation each for decomposition reactions where energy is supplied in the form of

heat, light or electricity.

Sol :

2Sunlight

Photo decomposition in the presence of sunlight

2 AgBr 2Ag Br

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2 2 2Electricity

Electro decomposition (by passing electricity through acidified water)

2H O 2H O

3 2

Thermal decomposition (by heat)

CaCO CaO CO

15. Compare the nervous and hormonal systems for control and coordination in human beings.

Sol:

Nervous Control Hormonal Control

1. It gives fast response. 1. Its response is slow

2. Information travels in the form

of chemical and electrical waves.

2. Information travels in the form of

chemicals.

3. It is has no effect on growth of

body.

3. It affects the growth of the body.

4. Its effects are short term. 4. Its effects may remain for long time period.

16. What is electrical resistivity? In a series, electrical circuit comprising a resistor made up of a

metallic wire, the ammeter reads 5 A. The reading of the ammeter decreases to half when the

length of the wire is doubled. Why?

Sol :

Electrical resistivity is the nature of a material to offer resistance to the flow of current of unit

length and unit area of cross-section.

Its symbol is .

(from R = × l

A) i.e. R l

whereas R 1

l (from

vR

I )

1

lI

Hence when length of wire is doubled, the reading of ammeter decreases to half.

17. What is the role of fuse, used in series with any electrical appliance? Why should a fuse with

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defined rating not be replaced by one with a larger rating?

Sol :

A fuse is having low melting point and high resistivity and allow of a limited maximum

current that can flow through it. When the current exceeds the maximum rated value, the fuse

melts and break the circuit, which prevents short-circuiting. A fuse with defined rating should

not be replaced by one with a larger rating, because the one with larger rating would allow a

larger amount of current to flow through it and will not break the circuit even if

short-circuiting is about to occur. Therefore, it can lead to short-circuiting and hence, is unsafe

to use.

18. Leaves of a healthy potted plant were coated with vaseline. Will this plant remain healthy for

long? Give reasons for your answer.

Sol :

If leaves of a healthy potted plant were coated with Vaseline, it would not remain healthy for

long. The plants photosynthesize and respire by taking carbon dioxide and oxygen through

air, respectively, and this is done by the stomatal pores present in their leaves. By coating with

Vaseline, the leaves would no longer be in contact with air and will not be able to take CO2 and

O2. Hence, they plant will die soon as they would not be able to prepare food for themselves

through photosynthesis and cannot respire too.

19. What are reflex actions? Give two examples. Explain a reflex arc.

Sol :

Sudden, unconscious, involuntary response to a stimulus is called reflex actions.

e.g., Knee jerk reflex, sneezing, coughing, etc.

During any reflex action, a message from receptors is relayed to sensory nerves to the spinal

cord, which sends information for response via motor nerves to effectors (which may either

be muscles or glands). This pathway is called as reflex arc.

Reflex arc is the path way through which the information travels to the spinal chord and then

the response is made.

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20. Observe the given figure and answer the following questions:

(a) Write the complete balanced reaction for the above.

(b) Type of reaction involved.

(c) Is there any precipitate formed?

(d) If any precipitate formed, write the colour of the precipitate.

Or

A student dropped few pieces of marble in dilute hydrochloric acid, contained in a test

tube. The evolved gas was then passed through lime water. What change would be

observed in lime water? What will happen if excess of gas is passed through lime water?

Write balanced chemical equations for all the changes observed.

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Sol :

(a)

2 4 2 4White

Na SO BaCl BaSO 2NaCl

(b) It is a double displacement section.

(c) Yes, a white precipitate of BaSO4 is formed.

(d) The colour of precipitate formed is white.

Or

(i) 3 2 2 2CaCO HCl CaCl H O CO

In this reaction CO2 gas is evolved.

(ii) Ca(OH)2 + CO2 CaCO3 + H2O

i.e. if excess of CO2 is passed through line water. It will again form CaCO3 (marble)

21. (a) Two circular coils A and B are placed closed to each other. If the current in the coil A is

changed, will some current be induced in the coil B ? Give reason.

(b) State the rule to determine the direction of a :

(i) Magnetic field produced around a straight conductor carrying current.

(ii) Force experienced by a current carrying straight conductor placed in a magnetic field,

which is perpendicular to it.

(iii) Current induced in a coil due to its rotation in a magnetic field.

Or

(a) When is the force experienced by a current carrying conductor placed in a magnetic field

largest?

(b) A coil of insulated copper wire is connected to a galvanometer.

What will happen if a bar magnet is:

(i) pushed into the coil ?

(ii) Withdrawn from inside the coil?

(iii) Held stationary inside the coil?

(c) Describe the activity that shows a current carrying conductor experiences a force

perpendicular to its length and the external magnetic field. How does Fleming's left-hand rule

help us to find the direction of the force acting on the current carrying conductor?

Sol:

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By changing current in the coil A, a current will be induced in the coil B which is placed close

to A. This is due to the reason that magnetic filed lines linked with A also get linked with B due

to its being close to A. When the current in A changes, magnetic field lines linked with A

change. Obviously, magnetic filed lines linked with B also change. This changes the flux linked

with B. As a result of this, current is induced in the coil B.

(b) (i) Land thumb rule

(ii) Fleming left hand rule.

(iii) Fleming right hand rule.

Or

(a) According to Fleming’s left hand rule, let the thumb, forefinger and central finger of the left

hand be stretched so that they are mutually perpendicular to one another. If the forefinger

points in the direction of the magnetic field and the central finger points in the direction of a

current, the thumb gives the direction of the force action on direction of the force acting on

the conductor.

(b) (i) When bar magnet is pushed into the coil due to electromagnetic induction an induced

current is produced. The galvanometer will show deflection.

(ii) Same as above but deflection will be in opposite direction.

(iii) No deflection.

22. Draw a neat diagram of internal structure of human heart and label the parts which do the

following functions.

(a) chamber where oxygenated blood from lungs is collected

(b) largest blood vessel in our body

(c) muscular wall separating right and left chambers

(d) blood vessel that carry blood from heart to the lungs.

Or

State three main events occurring during photosynthesis. Write the overall equation for

photosynthesis and the site for photosynthesis.

Sol :

See Labeled diagram of heart given in NCERT.

Or

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This main events occurring during photosynthesis are as follows :

(1) Absorption of light energy by chlorophyll in the leaves.

(2) Conversion of solar energy into chemical energy.

(3) Reduction of carbohydrates. to release energy.

2 2 6 12 6 2 2

Sunlight6H O 6O C H O 6O H O

Chlophyll

The chloroplasts present in cells of leaves are the site for photosynthesis as they contain the

green coloured pigment called chlorophyll.

23. (a) What is rock salt? How is it formed? Why is it brown in colour? How is it obtained?

(b) Why does blue color of copper sulfate solution start fading when a zinc rod is dipped in it.

(c) What is corrosion? Write the reaction representing the formation of rust.

(d) Give one example where corrosion is an advantage rather than a disadvantage.

Or

(a) Why the medium becomes acidic in mouth? What is the ill effect of this acidic medium?

How can this be prevented?

(b) A yellowish-white powder which smells of chlorine readily loses chlorine on exposure to

air, it is also used for bleaching cotton and for disinfecting water.

(i) Identify the yellowish-white powder compound.

(ii) Write balanced chemical equation representing the reaction involved in its manufacture.

Sol :

(a) When the carbohydrates present in are mouth are acted on by the bacteria present in the

mouth, as acidic substance called ethanoic acid (CH3COOH) is produced which makes the ph

level of the mouth fall below 55.

This is how an acidic medium is created in mouth and this causes covetiss and tooth decay.

This can be prevented by properly brushing out teeth. This removes the food stuck in a an

teeth and gums.

(b) (i) The yellowish – white powdered compound is bleaching powder (CaOCl2).

(ii)

2 22Chlorine gas bleaching powderlinewater

Ca OH Cl CaOCl

24. (a) Give a reason to explain why :

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(i) adrenaline helps in dealing emergency situations?

(ii) secretions of growth hormone should be specific in the human body?

(iii) some patients of diabetes are treated by giving injections of insulin?

(b) What will happen if intake of iodine in our diet is low ?

Or

(a) What is (i) phototropism and (ii) geotropism ?

With labelled diagrams describe an activity to show that light and gravity change the direction

that plant parts grow in.

(b) Mention the role of each of the following plant hormones:

(i) Auxin (ii) Abscisic acid

Sol :

(a) (i) Adrenaline helps in dealing emergency situations as it is secreted when are very energy

as emotional, when we get excited etc. This hormone gives us enormous amount of energy

which helps as in responding to situations.

For eg. When me are afraid or scared of a person and that person suddenly comes in front of

us, we start running.

(ii) Secretion of growth hormones should be specified in human beings as if it is secreted in

extensive amount, it may result in gigantism and it released quite less, then it may result in

dwarfism. Therefore it should be secreted in a normal amount.

(iii) Some patients of diabetes are given injections of insulin as during diabetes a

comparatively less amount of insulin is secreted which doesn’t check the sugar level in our

body. So, in order to maintain the sugar level in our body, some patients are given injections

of insulin.

(b) It intake of iodine in our diet is low, less amount of thysoseinc will be produced by the

thyroid gland which may finally lead to a disease named goiter due to deficiency of iodine.

Thus adequate intake of iodine is essential for an body.

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Section – B

25. A student took the following samples to find out their pH using pH paper. The teacher

remarked that one of the samples taken was not proper. The teacher was referring to:

(a) dilute hydrochloric acid (b) lemon juice (c) washing soda (d) soap solution

26. Four students a, b, c and d of class 10 measured the pH value of each one of the given samples

of distilled water, acetic acid, dil. hydrochloric acid and sodium hydroxide solution using pH

papers. Which one of the following represents a correct measurement ?

27. When zinc reacts with dilute hydrochloric acid :

(a) the surface of zinc becomes brighter(b) the surface of zinc becomes black and dull

(c) the metal turns into powder (d) the reaction mixture turns green

28. A drop of colourless liquid was placed on blue litmus paper. The litmus paper turned red. The

liquid could be :

(a) dil. hydrochloric acid (b) dil. sodium hydroxide solution

(c) distilled water (d) sodium bicarbonate solution

29. Aqueous solutions of zinc sulphate and iron sulphate were taken in test tubes I and II by four

students A, B, C and D. Metal pieces of iron and zinc were dropped, in the two solutions and

observations made after several hours and recorded in the form of a table as given below.

The correct reporting has been made in observation reported by the student:

(a) A (b) B (c) C (d) D

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30. Diagram showing a microscopic view of epidermal tissue

(a) is correct in all aspects (b) is wrong because stoma is not shown

(c) is wrong because the guard cells are directed backwards

(d) is correct because two guard cells stomata are present

31. 10 mL of freshly prepared iron ( sulphate solution was taken in each of four test tubes. Strips

of copper, iron, zinc and aluminium were introduced, each metal in a different test tube. A

black residue was obtained in two of them. The right pair of metals forming the precipitate is

:

(a) copper and zinc (b) aluminium and copper

(c) iron and aluminium (d) zinc and aluminium

32. Which of the circuit components in the following circuit diagram are connected in

parallel?

(a) R1 and R2 only (b) R2 and V only (c) R1 and V only (d) R1, R2 and V.

33. In the following circuits, heat produced in the resistor or combination of resistors connected

to a 12 V battery will be

(a) same in all the cases (b) minimum in case (i)

(c) maximum in case (ii) (d) maximum in case (iii)

34. You are given four resistors. If the resistance is to be increased, then the resistors are to be

connected in:

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(a) series (b) parallel (c) mixed arrangement (d) none of these.

35. The readings of current flowing through a conductor and the potential difference across its

two ends are shown in the ammeter and voltmeter given below. The resistance of the

conductor would be:

(a) 20 (b) 5.0 (c) 2.0 (d) 0.2

36. To determine the equivalent resistance of a series combination of two resistors R1 and R2, a

student arranges the following set up.

Which one of the following statements will be true for this circuit ? It gives :

(a) incorrect reading for current I and potential difference V both.

(b) correct reading for current I, but incorrect reading for potential difference V.

(c) correct reading for potential difference V but incorrect reading for current I.

(d) correct readings for both V and I.

37. In an experiment to show that sunlight is necessary for photosynthesis, the leaf is

boiled in alcohol for a few minutes using a water bath.

Water bath is essential because :

(a) alcohol is highly volatile

(b) steam from the water bath heats the leaf rapidly

(c) steam from the water bath dissolves the chlorophyll

(d) alcohol is inflammable

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38. Given here is a sketch of a leaf partially covered with black paper and which is to be

used in the experiment to show that light is

compulsory for the process of photosynthesis. At the end of the experiment, which one of

the leaf parts labeled I, II and III will become

blue- black when dipped in iodine solution,

(a) I only (b) II only (c) I and III (d) II and III

39. Which structure out of I,II,III and IV marked in the given diagram of the epidermal peel of

leaf should be labeled as stoma ?

(a) I (b) II (c) III (d) IV

40. The teacher instructed a student to place a healthy potted shoe flower plant in a dark

room for 24 hours prior to an experiment on photosynthesis. The purpose of placing it in

a dark room is :

(a) to increase the intake of CO2 (b) to activate the chloroplasts in the leaves

(c) to destarch the leaves (d) to denature the enzymes in the leaves.

41. In the sketch of the stomatal apparatus given:

Which one of the following is missing?

(a) cell membranes of the cells (b) cell walls of the cells

(c) nuclei in the guard cells (d) chloroplasts in the guard cells

42. Two solutions A and B were found to have pH value of 6 and 8

respectively. The inference which can be drawn is:

(a) The strength of solution B is higher than that of A. (b) A is an acid while B is base.

(c) Both are acidic solutions. (d) Both are basic solutions.

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ANSWERS

25 C 26 D 27 B 28 A 29 C

30 C 31 D 32 D 33 C 34 A

35 A 36 B 37 D 38 C 39 D

40 C 41 C 42 B

All The Best

10th CBSE{SA I} Pioneer Education - · PDF file · 2013-09-05Pioneer Education...

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Transcript of 10th CBSE{SA I} Pioneer Education - · PDF file · 2013-09-05Pioneer Education...