HSE I Chemistry March 2013

8/13/2019 HSE I Chemistry March 2013

1/11

F.Y.March 2013 516

ar t IIICHEMISTRY

Maximum: 60 ScoresTime : 2 Hours

Cool offtime: 15 Minuteseneral Instructions to dandidates There is a 'Cool off time of 15 minutes in addition to the writing time of 2 hrs.. . ' . . You are neither allowed to write your answers nor to discuss anything with

o t h ~ r s during the 'cool off time . Use the 'cool off time to get familiar with questions and to plan your answers. Read the questions carefully before answering. All questions are compulsory and only internal choice. is allowed . When you select a question, all the sub-questions must be answered from the

same question itself. Calculations, figures and graphs should be shown in the answer sheet itself.e Malayalam version of the questions is also provided. Give equations wherever necessary. Electronic devices except nonprogrammable calculators are not allowed in theExamination HalL

m1 ro cs< CRl6lll 3 ciO :

K-32

e m1&(31osJs ffi)Q)CQ.J(O'(Q)1mu CLIJ,OGlQ) 15 Q)1m18 'c&,J,cf6 @:)o.Ou 6)6)So' ~ 6 l I S O c 6 J l C 0 1 c B 6 l J p . gQ Dffi)Q)CQ.JO)


2/11

1. The mole concept helps in handlinga large number of atoms andmolecules m stoichiometriccalculations.a) Define 1 mol.b) What is the number of hydrogen

atoms in 1 mole of methane

c) Calculate the amount of carbondioxide formed by the completecombustion of 80 g of methaneas per the reaction :

Atomic masses : C = 12.01u,H = l.008u, o = 16u).

2. Photoelectric effect was firstobserved by Hertz.a) The number of electrons ejected

in the photoelectric effect isproportional to ............. of .lightused. (frequency, intensity).

I

b) Select the correct statementrelated to the photoelectriceffect :

K 32

i) Threshold frequency is themaximum frequencyrequired to causephotoelectric emission froma particular metal.

1)

2)

1)

2

1 < l l ~ C J c 0 0 1 < l l W 8 6 ' Q l l S 1 c e ; 'c f u 6 m c 0 0 6 d b ~ e J 2 , c f u ~ 6 Q ) C J @ 1m1roruw1 \ Q l C l l c f u < l l ~ W . , o 6l6lcfucfuCJ((),jo 6 l D J ~ O c i Oa:m iD eJU


3/11

ii) The kinetic energy of thephotoelectrons is directlyproportional to thefrequency of incident light.

iii) Work function is the same forall metals.

3. The general features of thestructure of a hydrogen atom andhydrogen like species werequantitatively explained by NielsBohr.a) Write any postulate Of the

Bohr s model of the hydrogenatom.

b) Calculate the radius of thesecond orbit of .(Express the answer in nm).

RThe dual behavior of matter wasproposed by the French physicist,de Broglie.a) State the dual behavior of

matter.b) A moving electron has a

de Broglie wavelength of7 X IQ-7m. Calculate its kineticenergy.

1)

1)

2)

1)

(Planck s constant= 6. 626 x 10-34 J s,Mass of an electron= 9.1 x 10-:11 kg). 2)

K-32 3

nJ(lj)ffiL J cfu o IO (O(lj)16l aJ@ (O(lj)1 cQ.rcHll


4/11

4 The reactivity of an element is very ..much related to its ionizationenthalpy.a) In general, ionization enthalpy

increases from left to rightacross a period. Give the reason. 1)

b) Observe the following graph nwhich the first ionizationenthalpies (L\ .H of elements oflthe second period are plottedagainst their atomic numbersZ):

2500

... 20008

~ 1500 .~< .

1000

4

4. ~ ( 1 ) 6 alJeJcfu(OY0)16l


5/11

o A molecule of h ~ type 3E2':1as three bond pairs and twolone pairs of electrons. Px:-edicttne most stab arrangement ofelectron pairs in this molecule. ( 1)

cl The bond order value 1s animportant property of amolecule. How is bond orderrelated to bopd length?

d) Write the electronicconfiguration of an oxygenmolecule arid justify i tsmagnetic nature.

6. Real gases behave ideally only atcertain conditions.a) Wnat is Boyle point of a gas?b) Write the express10n for

compressibility factor. What is

(1)

(2)

(1)

its value for an ideal gas? (1)c) Density of a gas was found to be

5.5 gL-1 at 2 bar pressure.Calculate its molar mass.(R = 0.083 bar L mol-1 K-1 .

K-32

(2)

5

dbillOLCllJ1 illJrrn" Ql6Yll86fl'S" G l ~ o s 1gQe.JcfuGl LS06m6cfu6o m6' 1i GleJOG'liO G l ~ O S 1@ eJ cfu ]lL 0 6'11) 6cfu @.6 0 gJ_ 6fl'S" @ Dem ill o UOl w1 gQ eJ cBo Gl L o 6'liOG l ~ O S 1 c f u @ _ 6 6 l S o@80J6o mill1alW2,@[email protected] o ill cBoffi6mo L J ru. Lll c006 Bo.

c) 63al2, cfilillOLW2,6lS loJWOffi6l


6/11

7. Most of the natural ly occurringprocesses are spontaneous.

a) Give the criteria 'for spontaneityof a process in terms of freeenergy change ( c1 G). (,1)

b) Exothermic reactionsassociated with a decrease Inentropy are spontaneous atlower temperatures. Justify onthe basis of Gibbs equation.

c) Find the temperature abovewhich the reaction

becomes spontaneous.(Given L H 0 = 490 kJ mol-1 andr

1)

L1rH 0J = 198 J K mol-1) . (2)8. Equilibrium is possible only in a

closed system a t a giventemperature.a) Write the expression for

equilibrium constant, Kc for thereaction.4NH., gJ + 5 0 g ) ~ 4 N O g ) +

(1)

b) What happens to the value of theequilibrium constant (K'c) when theabove reaction is reversed? 1)

K-32 6

7. l n . J c f u ~ 1 C W 1 e . J J , ~ m1cOOCl.JOOJ,o %)BOln.J l fu1cwctb60 ffi)u6)n.J 0Gl6n'S mi cw cpJ' ffi'@ 611'l.'a) loill, owmrog;1 O J c \ j O m J W 0 ) 1 6 J ~

O s1 ffilD om llYO)1 fi 8 (2 G) 63m2ln.J lcfu1 WCWJ,61S uLl 61n.JOGl6n'S rr,i g1 CWJ,61SmomG6TilJ.Jo oB)'l'J,J,cB:,.

b) %)rfD


7/11

9. \\ 2 . ~ - \ . acids are partially ionized inaq ~ _ : e : ~ . : s solutions.

K-32

a) l ~ : c - ~ o n i z a t i o n constants of somes ~ d s are given below :

AcidiI L:rmic acid HCOOH)j :Ic....::Jmtcili' al@cmiM {HCOOH)I Hypochlorous acid HClO)

6 l 6 l n D ~ < ~ : J O ~ ~ o o c r u m-cru1cu) (HCZO)I : \itrous acid HN02)

86l(')LSmJ ~ C l ' J c u ) HNO?)Hydrocyanic acid H C 1 \ ~

6 l 6 l n . O ~ LwocruCQ m1cfu' aJ@ crD1 cu) (HCN)

Arrange the above acids in theincr.easing order of their acidstren;:;th. 1)

b) Calculate the pH of a 0.01 _Macetic acid solution with thedegree of ionization 0.045. 2)

ORSalts can be classified into differentcategories on the basis of theirsolubility.a) Identify the solubility range of

sparingly soluble salts from thefollowing :(Between 0.01 :\II and 0.1 M, lessthan 0.01 M greater than O.lM). 1)

bl Calculate the soiubility S) ofC a S O ~ . at 298 K if its solubilityproduct constant Ksp) at thistemperature is 9 x lQ -6. 2)

7

9 o.Jlro,1o c6:l6061GYID al@cru1CLJJ6c6:lcib 816el1WeJowm1 w1 co'O cso 1)1 ce:, Qlow1(lffi) wo6'rl11 ce:,ro1 dJUJ3rm6a) ill1 eJ 0 cru1 CLJJ 6c6:l 6l s(lffi) (Q)0 6l 6l6m \flJ nS:HYO ffiill1 (() 0 ffi:> 6llB ci

06l':P 6lcB:lOS60l1ro1dJUJ.?,\ffi6.

Ionization constant K). a(lffi)GJW 6l6l6mo

1.8 X lQ -4

3.0 X lQ-S

4.5 X lQ -4

4 9 X 10-10

a l 6 c B ~ 1 co'O r m 3 6 ~ 0 r u 1 C L J J 6 c 6 : l 6 l ~(lffi)0J(Q)66lS (lffi)\fll1CLJJ1ce:,v "iLOJW66lS

516

ffi"@Cl(()OnDGm lcB:lalOl1co'O. ng)lf'66c6:l. (1)b) CLJJ1l(J)1 630n.Ov (lffi)6) ( Q ) 0 6 l 6 l 6 T D ~ \fl)nS:J r:iiJ

o. 045 2 . ~ o o1 C l Q l o ~ o r u (lffi)6lcru81v:h.ro'@\fll1CLJJv eJOWm1W66lS pHc&.i6mdJUJOdJUJ6c6:l. (2)

am 6) ~ ab1 c O


8/11

10. Competitive electron t ransferreactions are uti l ized m theconstruction of Galvanic cells.a) Write the redox reaction

involved when metallic cobalt isplaced in a nickel sulphatesolution.(Note : Only the ionic reactionis expected).

b) In the reactionPb(s) + PbQZ(s) + H2S0 4aq)

PbS s) + 2 H 20(1l,identify the following :i) Substance oxidizedii) Substance reducediii) Oxidizing agentiv) Reducing agent

11. About 18 of the total productionof dihydrogen is from coal.

1)

(2)

a) What is 'coal gasification ? (1)b) How is dihydrogen produced by

a water-gas shift reaction ?c) Write any two uses of

dihydrogen.

K-32

(2)

1)

8

10 (]cf:b:JoCJ..JRIRioJ 221c:buG5[S8611'0 [S::xr'DmJ"o_occlCJ..J 1[ l..J OJ r (00) m 6013 cJD l) 0 mil OJ 0 m1 cf:bo6)CillBJ,cf:b_J,6)S mii'O 11ril06m(00)1 mu

~ C l . . J ( ] ( Q J : ) C / ) 1 c B t i l J , f f i l J , .

a 6) c:b o6ill o 1J a eJ ooD 6) (00) m1 c06 m DmJ(;1J(]oJ) Ru eJ OCQJm CQJl ro IJ OJ Q}c86)6] ffiJ:) cJD

( ()6)CQJ:J6m1cfu [CJ..J@l[oJOJi'OIOmo Ql:J[(Q)o. ng)lf'J,1CQJ:Jafb Ql8'J-,CQJ0c&o6o. :

b) Pb( l + PbO?( ; + 2H 980 4 .s - " - aqPbS 4 s) -r 2 H 20( ) r


9/11

12. Alkali metals and alkaline earthmetals belong to the S-block of theperiodic table.a) Name the process used for the

industrial preparati'lm ofsodium carbonate.

b) The above mentioned method isnot suitable for the preparationof potassium carbonate. Givethe reason.

1)

1)c) Draw the chain structure of

beryllium chloride in solid state. (1)d Write the chemical equation

showing the preparation ofPlaster of Paris from gypsum. 1)

12. @'@lam c00en g e1 onn 6N3 2 , o @ @) amc00 6) 6) eJmntJ> 6 @()) G eJ on 6oB o @'@l ru 6 curm mo.J1ctt,CW2,6)S S - < N 6 Q d O ~ , , o 6 ~ c i 1 l @ < ; t j 5 6 c m ~ .a) cg cru o cullw o

O J ~ o ru cru ow1 ctt,~ rL Cl CQ f)/ cOO6 f i

ctt, o 66ill


10/11

14. The IUPAC names of alkanes arebased on their chain structure.a) Give the IUPAC name of

CH CH CH CH CH CH CHJ 2 2 2 3I I

b) R e p r e s ~ n t 1-Methyl-3- propylcyclohexane using bond linenotation.

c) What l the type ofhybridization of C in 3 ? Alsopredict its shape.

d) N arne the type of bond fissionresulting in the formation offree radicals.

OR

Organic compounds have to bepurified before analysis.a) Which type of liquids can be

purified using distillation underreduced pressure? Suggest anexample.

b) Name the two main types ofchromatographic techniquesbased on the principle ofdifferential adsorption.

c) In the Lassaigne s test forhalogens, they are precipitated

1)

1)

(i)

1)

1)

1)

as............... (1)d) In what form IS nitrogew

estimated m .the Dumasmethod? (1)

K 32 10

14.


11/11

15. Many chemical propert ies oforganic compounds can beexplained on the basis of electrondisplacement effects.a) What is a resonance effect? (1)b) Categorize the following

functional groups into thosehaving +R effect and -R effect:

-NH 2 N 2 --COOH, -OH (1)16. Free rotat ion 1s possible with

respect to a C-C bond in the caseof alkanes.a) The repulsive interaction

betvveen the adjacent bonds in aconformat1on is called ........ .

b) Draw ::\ewman s projections ofthe two conformers of ethane.

Which among these is morestable? Justify.

c) An alkene on ozonolysisfollowed by reduction of theozonide formed with zinc andwater gave a mixture of ethanaland methanal.i) Identif)r the alkene.ii) Illustrate the above

mentioned reaction using thechemical equation.

17. Pollution of water originatesmainly from human activities.

(1)

(2)

(1)

(1)

51615 cfuO ro6W 61TJ1d3:> m.JoCQ 6ce6l B66l S ill1ch>'"l

(b 0 ffi) U) 6 1TJ 6lJB 6Q g)2 eJ cfuuGllS :J 6 1'6\J)l ffi)u 6) 6 l +R ~ n . O c f u S 6 ~ Q J 6 ) C Q ( f f i 6 o- R g)2 n.O .

-NH2 -N 02 , -COOH, -OH (1)16 C-Gl6W06Tl'S16lm Cl.l"@WOCllillOcB6l1

aJm) am Gl cB6) m6 fu1 am ffi)J Q) lmJ) ill 0 ill u ill61TJ 0m.JOW,)illOGTT).a) 63C06 ca:,6Y"ill Gl n.OOill o16l eJ m.Jilli o..J crun

Gl6W06Tl'S6cfuem am1eJ6 o . J l c a : , r o m : ~ 6 1 T J 6 l C O " . Cl{j)(ffi6oJlglc006(ffi6 1 )

b) g)2 0 Gll.O 6) < 5 (l) 6f1'5u ch 6Y"ill ]l n.Q 0 ll 0 6 fu 6)Sm J,illOffi> 6)l ..JOg16dhl:J ffi6cfuem ru CllWcB6l6cfu.g)2 /j)1 m o.ffi /j)1m0 611) mill1 (b (Q)[email protected]? m . J O W ~ c f u C O l c B 6 l 6 c f u . (2)

c) 63Cb2, anmaruc00'16lm 6306)m.J0Glffi01m.J1m.Jum s C0"1 eJ cs1 .?J, 63 o6) cru o6l 6l 6f() (U)16l mcru1 B:h6o g16 eJ ru 6o o..J aw owb,miGlcoocfu'crui ca:, co1.8,l Gl

HSE I Chemistry March 2013

Documents

Transcript of HSE I Chemistry March 2013