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Board Paper of Class 12-Science 2013 Chemistry All India(SET 2) - Solutions

General Instructions:
(i) All questions are compulsory
(ii) Question numbers 1 to 8 are very short-answer questions and carry 1 mark each.
(iii) Question numbers 9 to 18 are short-answer questions and carry 2 marks each.
(iv) Question numbers 19 to 27 are also short-answer questions and carry 3 marks.
(v) Question numbers 28 to 30 are long-answer questions and carry 5 marks each.
(vi) Use Log Tables, if necessary. Use of calculators is not allowed.
  • Question 1

    Write the structure of 2-aminotoluene. (1)

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  • Question 2

    Which aerosol depletes ozone layer? (1)

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  • Question 3

    Of physisorption or chemisorptions, which has a higher enthalpy of adsorption? (1)

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  • Question 5

    Write the IUPAC name of the following compound:

    (1)

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  • Question 6

    Name the method used for refining of copper metal. (1)

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  • Question 7

    Write the name of linkage joining two amino acids. (1)

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  • Question 8

    Give one example of a condensation polymer. (1)

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  • Question 9

    (a) Why does presence of excess of lithium makes LiCl crystals pink?

    (b) A solid with cubic crystal is made of two elements P and Q. Atoms of Q are at the corners of the cube and P at the body-centre. What is the formula of the compound? (2)

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  • Question 10

    Write the equations involved in the following reactions:

    (i) Reimer − Tiemann reaction

    (ii) Williamson’s ether synthesis (2)

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  • Question 11

    Define thermoplastic and thermosetting polymers. Give one example of each. (2)

    OR

    What is a biodegradable polymer? Give an example of a biodegradable aliphatic polyester.

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  • Question 12

    Explain the mechanism of the following reaction: (2)

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  • Question 13

    How are interhalogen compounds formed? What general compositions can be assigned to them? (2)

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  • Question 14

    Draw the structures of the following molecules:

    (i) XeF6

    (ii) H2S2O7(2)

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  • Question 15

    Aluminium crystallizes in an fcc structure. Atomic radius of the metal is 125 pm. What is the length of the side of the unit cell of the metal? (2)

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  • Question 16

    The standard electrode potential (E°) for Daniell cell is + 1·1 V. Calculate the ΔG° for the reaction (2)

    (1 F = 96500 C mol−1).

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  • Question 17

    (a) For a reaction A + B → P, the rate law is given by,

    r = k [A]1/2 [B]2.

    What is the order of this reaction?

    (b) A first order reaction is found to have a rate constant k = 5·5 × 10−14 s−1. Find the half life of the reaction. (2)

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  • Question 18

    Outline the principles of refining of metals by the following methods: (2)

    (i) Zone refining

    (ii) Vapour phase refining

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  • Question 19

    Define the following terms giving an example of each: (3)

    (i) Associated colloids

    (ii) Lyophilic sol

    (iii) Adsorption

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  • Question 20

    Calculate the emf of the following cell at 25°C : (3)

    Given E°cell = + 0.46 V and log 10n = n.

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  • Question 21

    Shanti, a domestic helper of Mrs. Anuradha, fainted while mopping the floor. Mrs. Anuradha immediately took her to the nearby hospital where she was diagnosed to be severely ‘anaemic’. The doctor prescribed an iron rich diet and multivitamins supplement to her. Mrs. Anuradha supported her financially to get the medicines. After a month, Shanti was diagnosed to be normal. (3)

    (i) What values are displayed by Mrs. Anuradha?

    (ii) Name the vitamin whose deficiency causes ‘pernicious anaemia’.

    (iii) Give an example of a water soluble vitamin.

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  • Question 22

    Write the man products of the following reactions: (3)

    (i)

    (ii)

    (iii)

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  • Question 23

    The rate of a reaction becomes four times when the temperature changes from 293 K to 313 K. Calculate the energy of activation (Ea) of the reaction assuming that it does not change with temperature.

    [R = 8·314 J K−1 mol−1, log 4 = 0·6021] (3)

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  • Question 24

    For the complex [NiCl4]2−, write (3)

    (i) the IUPAC name.

    (ii) the hybridization type.

    (iii) the shape of the complex.

    (Atomic no. of Ni = 28)

    OR

    What is meant by crystal field splitting energy? On the basis of crystal field theory, write the electronic configuration of d4 in terms of t2g and eg in an octahedral field when

    (i) Δ0 > P

    (ii) Δ0 < P

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  • Question 25

    Give reasons for the following : (3)

    (i) Ethyl iodide undergoes SN2 reaction faster than ethyl bromide.

    (ii) (±) 2-Butanol is optically inactive.

    (iii) C − X bond length in halobenzene is smaller than C − X bond length in CH3 − X.

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  • Question 26

    (i) What class of drug is Ranitidine? (3)

    (ii) If water contains dissolved Ca2+ ions, out of soaps and synthetic detergents, which will you use for cleaning clothes?

    (iii) Which of the following is an antiseptic?

    0.2% phenol, 1% phenol

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  • Question 27

    Give reasons for the following : (3)

    (i) Oxygen is a gas but sulphur is a solid.

    (ii) O3 acts as a powerful oxidising agent.

    (iii) BiH3 is the strongest reducing agent amongst all the hydrides of Group 15 elements.

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  • Question 28

    (a) How will you convert the following : (5)

    (i) Propanone to Propan-2-ol

    (ii) Ethanal to 2-hydroxy propanoic acid

    (iii) Toluene to benzoic acid

    (b) Give simple chemical test to distinguish between :

    (i) Pentan-2-one and Pentan-3-one

    (ii) Ethanal and Propanal

    OR

    (a) Write the products of the following reactions :

    (i)

    (ii)

    (iii)

    (b) Which acid of each pair shown here would you expect to be stronger?

    (i) F — CH2 — COOH or Cl — CH2 — COOH

    (ii)

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  • Question 29

    (a) State Raoult’s law for a solution containing volatile components.

    How does Raoult’s law become a special case of Henry’s law?

    (b) 1·00 g of a non-electrolyte solute dissolved in 50 g of benzene lowered the freezing point of benzene by 0·40 K. Find the molar mass of the solute. (Kf for benzene = 5·12 K kg mol−1) (5)

    OR

    (a) Define the following terms :

    (i) Ideal solution

    (ii) Azeotrope

    (iii) Osmotic pressure

    (b) A solution of glucose (C6H12O6) in water is labelled as 10% by weight. What would be the molality of the solution?

    (Molar mass of glucose = 180 g mol−1)

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  • Question 30

    (a) Give reasons for the following : (5)

    (i) Mn3+ is a good oxidising agent.

    (ii) values are not regular for first row transition metals (3d series).

    (iii) Although ‘F’ is more electronegative than ‘O’, the highest Mn fluoride is MnF4, whereas the highest oxide is Mn2O7.

    (b) Complete the following equations :

    (i)

    (ii)

    OR

    (a) Why do transition elements show variable oxidation states?

    (i) Name the element showing maximum number of oxidation states among the first series of transition metals from Sc (Z = 21) to Zn (Z = 30).

    (ii) Name the element which shows only +3 oxidation state.

    (b) What is lanthanoid contraction? Name an important alloy which contains some of the lanthanoid metals.

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