isc 2012 chemistry paper-1 question paper

8/2/2019 ISC 2012 Chemistry Paper-1 Question Paper

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CHEMISTRYPaper-l

(THEORY)(Three Hours)(Candidates are allowed additional 15 minutes for only reading the paper:

They must NOT start writing during this time.)- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ~ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -Answer all questions in Part I and six questions from Part IL choosing two questions

from Section A, two from Section B and two from Section C.All working, including rough work, should be done on the same sheet as, and adjacent to,

the rest of the answer.The intended marks for questions or parts of questions are given in brackets [ ].Balanced equations must be given wherever pos-sible and diagrams where they are helpful.

When solving numerical problems, all essential working must be shown.In working out problems use thefollowing data:

Gas constant R = 1.987 cal deg" mol" = 8.314JK-1 mol-l =0.0821 dm' atm K -lmoCl1 I atm = 1dm3 atm = 101.3 J 1Faraday = 96500 Coulombs.

PART IAnswer alt questions

Question 1(a) Fill in the blanks by choosing the appropriate word/words from those given in the brackets: [5]

(Raoult's, Arrhenius, lateral, sodium, magnesium, negative, positive, non-ideal, ideal, iron,copper, van't Hoff, s, p, ethanol, ethanoic acid, methanoic acid, methanol, propanoic acid.)(i) For a spontaneous change to take place, the ~S of the system should be __ and ~G

of the system should be_---:- __(ii) Hydrolysis of methyl propanoate gives and _(iii)(iv)(v)

Solutions which strictly obey law are called solutions.--- -----n : bonds are formed by the overlap of orbitals.Zinc can displace from CUS04 solution, but cannot displace fromMgS04 solution.

1212-862 A Copyright reserved.This paper consists of 8 printed pages.

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(b) Complete the followingstatements by selecting theeorreet alternative from the-choices [5]grveru-(i) The quantity of electricity required to deposit 115g of sodium from molten

NaG (Na=23, Cl =5-5) is:(1) I F(2) O -S F(3) ()OSF(4) 15F

(ii) When acetic acid is reacted with calcium hydroxide and the product is distilled dry, thecompound formed is:(I) Calcium acetate(2) Acetone(3) Acetaldehyde(4) Acetic anhydride

(iii) The [OH-] concentration of a weak base is given by:(1) ckb(2) J C k b(3) 1-~ k Y c(4) ~

(iv) In a plot of log k vs liT, the slope is:(1) - Ea/2303(2) Eal2303 R(3) Ea/2303(4) - Eal2303 R

(v) Among the following coordination compounds, the one giving a white precipitate withBaCh solution is:(1) [Cr(H20)5Br]Sn~(2) [Cr{H10)5SCN](3) [Co(NH3)SS04]Br(4) {Pt(NH3)6]C4

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(c) Answer the following questions:0) A solution X is prepared by dissolving three moles of glucose in one litre of water and

a solution Y is prepared by dissolving 15 moles of sodium chloride in one litre ofwater. Will the osmotic pressure of X be higher~ lowr or equal to that of Y? .Give areason for your answer.

(ii) Give one example (equation) of a homogeneously camlysed reaction and name thecatalyst.(iii) Write the formula of the product formed when formaldehyde reacts with ammonia andname the product.(iv) If the ionization (dissociation) constant of acetic acid E S Ka. what win be tb e p H of a

solution containing equalconcenteatioes of acetic acid and sodium acetate?(v) What is the electronic configuration of chromium atoJ_IJZ =24)? Give a reason foryour answer.

(d) Match the following:

[5]

[5 1(i) Nemst equation(ii) Lactic acid(iii) Amphiprotic solvent(iv) Lewis base(v) Isocboric process

(a) Water(b) Constant volume(c) Ammonia ..(d) Optical isomers(e) Electrochemical ceUs

PARTllAnswer six questions choosing two from Section A. two frum

Section B anti two from Section C.SECTION A

Answer any two questionsQuestion 2(a) [i) A solution of urea in water has a boiling point of JOou,oe. Calculate the freezing (2}

point of the sol.ion. (Kr for water is 186K kg morl and Kbc-for water is0512 K kg mol"),(ii) A solution of lactose containing 845 g of lactose in rOOg of water has a vapour [31

pressure of 4559 mm of Hg at a G e . If the vapour pressure of pure water is4-579 mm of Hg, caiculate,the molecular weight oflaetese,

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(b) (i) The molecular weight of H2S is more than that of H20, but H2S is a gas and H20 is a [2]liquid. Explain.(ii) When potassium cyanide reacts with water, will the resulting solution be acidic, [2]alkaline or neutral? Justify yeur answer. - ,

(c) What is the hybridisation of the carbon atom in ethyne molecule? What is the H- C - H [1]bond angle?

Question 3 ..(a) (i) State the second law of thermodynamics in terms of the entropy of the universe. [1]

(ii) Calculate the maximum work that can be obtained from the given electrochemical cell [3]constructed with two metals Mand N.[E~+~ =-0.76V, E~+%=+0.34V]The cell reaction - i s M + N+ 2 - - ?M+2+ N

(b) (i) To precipitate group 1II cations NH 4Cl should be added to the solution before the [2]addition of ammonium hydroxide. Explain Why.(ii) A study of chemical kinetics of the reaction A+B -eproducts, gave the following data [2]at 25C:

Experiment [A] [ B ] d[Products]dt

1 1 .0 0.15 4.20 x 10-02 2 :0 0015 8AO x 10-0J 1 .0 0.20 5;-60 x 10-0

Find:(1) The order of reaction with respectto A.(2) The order of reaction with respect to B.(3) The rate law.

(c) (i) What are F-centres in an ionic crystal?(ii) Why are crystals having F-centres paramagnetic?

[1][1]

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Question 4(a) (ir

(ii)

(b) (i)(ii)

The central atom of methane and water is in the same state of hybridisation, but the [2]shapes oft.tre'two molecules.are different. Discuss.The conductivity of 02M KCI solution is 3xI0-2ohm-1cm-l Calculate its molar [2]conductance.Draw the .valence shell molecular orbital diagram of oxygen molecule and predict its [2]magnetic nature.Calculate the solubility of lead chloride in water, if its solubility product is 17 x io', [2](Ph =206, Cl =355)

(c) For a crystal of diamond, state:(i) The hybridisation of the carbon atom.(ii) The.coordination number of each carbon atom.(iii) The type of lattice in whichitcrystalises,(iv) The number of carbon atoms present per unit cell.

[2]

SECTIONBAnswe any two questions

Question 5(a) Wl'ite-the.,formulae of the following coordination compounds:

(i) potassiumtetracyanonickel(O)(ii) triammirretrin itrocobalt(III)

(b) [CoF6ts a coordination complex ion.(i) What is the oxidation number of cobalt in the complex?(ii) How many unpaired electrons are there in the complex?(iii) State the magnetic behaviour of the complex.(iv) Give the I.U.P.A.C. name of the complex.Draw the structural isomer of [Co(NH3)sN02]Ch and name the type of isomerism.!

[2]

- [2]

(c) [1]

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Question 6(a) Give the equations for the conversion of argentite (AglS) to metallic silver.(b) Give balanced equations for the following reactions:

(i) Acidified potassium permanganare and oxalic acid.(ii) Ozone and mercury.(iii) Action of heat on a mixture of sodium chloride and concentrated sulphuric acid.

[2)(3)

Question 7(a) Explain why transition metals form complex compounds.(b) (i) What is the hybridisation of the chlorine atom in CIF 3molecule?

(ii) Draw the structure of the molecule and state its geometry.(c) Name the inert gases used for:(i) Filling sodium vapour lamps.

(ii) Obtaining light of different colours in neon signs.

[2][2 1

[I}

SECTIONCAnswer any two questions

Question 8(a) How can the following conversions be brought about:

(i) Ethanol to methylamine.(ii) Benzene to phenol.

(b) Complete the following reactions and name the reactions:(i) + 3h + 4KOH-)- CHI3 +CH3COOK + 3KI + 3H20(ii) C3H1NH2+CHC13+ 3KOH(alc.)~ +3KCI + 3H20

[3 1[2][3]

(c) Name the type of polymerisation (addition or condensation) and name the monomers in (2 1each of the following polymers:(i)(ii)

ProteinPolyethylene

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Question 9(a) (i) What type of isomers are glucose and fructose?

(ii) Name the functional group common to both glucose and fructose.(b) (1) Identify the products A, B and C:

[1 J

[3CH3o Alk.KMnO. ANaOH,CaOA (soda lime) B1 CI", FeCI, .

c( i j )

(c) Give balanced equations for the following reactions:(i) Benzaldehyde and hydroxylamine.(ii) Benzoic acid and phosphorous pentachloride.(iii) l-butanol and hydrogen chloride.

(d) Give one good chemical test to distinguish between the following pairs of compounds: [3](i) Methanal and ethanal.

[3]

(ii) Urea and benzoic acid.

Question 10(a) An aliphatic hydrocarbon A on treatment with sulphuric acid in the presence ofHgS04 yields [4]a liquid B with molecular formula C2RtO. B on oxidation with acidified potassiumdichromate yields C which gives effervescence with sodium bicarbonate. C when treatedwith SOCh gives D. When D reacts with ethanol it gives a sweet smelling liquid E. E is alsoformed when C reacts with ethanol in the presence of cone, H2S04

(i) . Identify A, B, C, D and E.(ii) Draw the structure ofthe isomer of compound B.(iii) Write the balanced equation for the conversion of A to B.

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(b) (i) The compound C6H12 shows optical isomerism. Draw the structural formula of the [1 ]compeund.andname it.

(ii) -Name any three.types'of isomerisms that the compound with 'molecular formula [3]C4H7Cican give rise to. Also representthe.structures of th compounds relevant tothese isomers.

(c) Give equations to show what happens when a mixture of potassium cyanate and ammonium [2]sulphate is strongly heated: Name the reaction.

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isc 2012 chemistry paper-1 question paper

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