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Board Paper of Class 12-Science 2016 Chemistry (SET 2) - Solutions

General Instructions :
(i) All questions are compulsory.
(ii) Q. no. 1 to 5 are very short answer questions and carry 1 mark each.
(iii) Q. no. 6 to 10 are short answer questions and carry 2 marks each.
(iv) Q. no. 11 to 22 are also short answer questions and carry 3 marks each.
(v) Q. no. 23 is a value based question and carry 4 marks.
(vi) Q. no. 24 to 26 are long answer questions and carry 5 marks each.
(vii) Use log tables if necessary, use of calculators is not allowed.

  • Question 1

    Write the IUPAC name of the given compound :


  • Question 2
    Write the structure of an isomer of compound C4H9Br which is most reactive towards SN1 reaction. VIEW SOLUTION

  • Question 3
    What is the reason for the stability of colloidal sols? VIEW SOLUTION

  • Question 4
    Give an example each of a molecular solid and an ionic solid. VIEW SOLUTION

  • Question 5
    Pb(NO3)2 on heating gives a brown gas which undergoes dimerization on cooling? Identify the gas. VIEW SOLUTION

  • Question 6

    For a reaction : H2 + Cl2      hv     2 HCl

    Rate = k

    (i) Write the order and molecularity of this reaction.
    (ii) Write the unit of k.


  • Question 7

    Write the chemical equations involved in the following reactions:

    (i) Hoffmann-bromamide degradation reaction
    (ii) Carbylamine reaction


  • Question 8
    (i) Gas (A) is more soluble in water than Gas (B) at the same temperature. Which one of the two gases will have the higher value of KH (Henry's constant) and why?

    (ii) In non-ideal solution, what type of deviation shows the formation of maximum boiling azeotropes? VIEW SOLUTION

  • Question 9

    When a coordination compound CoCl3.6NH3 is mixed with AgNO3, 3 moles of AgCl are precipitated per mole of the compound. Write

    (i) Structural formula of the complex

    (ii) IUPAC name of the complex


  • Question 10

    Write the structures of the following:

    (i) BrF3
    (ii) XeF4

    What happens when:

    (i) SO2 gas is passed through an aqueous solution Fe3+ salt?
    (ii) XeF4 reacts with SbF5?


  • Question 11
    Write the final product(s) in each of the following reactions:





  • Question 12
    How do you convert:
    (i) Chlorobenzene to biphenyl
    (ii) Propene to 1-iodopropane
    (iii) 2-bromobutane to but-2-ene


    Write the major products(s) in the following:





  • Question 13
    (i) Write the structural difference between starch and cellulose.

    (ii) What type of linkage is present in Nucleic acids?

    (iii) Give one example each for fibrous protein and globular protein. VIEW SOLUTION

  • Question 14
    (i) Name the method of refining of nickel
    (ii) What is the role of cryolite in the extraction of aluminium?
    (iii) What is the role of limestone in the extraction of iron from its oxides? VIEW SOLUTION

  • Question 15
    Give reasons:

    (i) SO2 is reducing while TeO2 is an oxidizing agent.

    (ii) Nitrogen does not form pentahalide.

    (iii) ICl is more reactive than I2. VIEW SOLUTION

  • Question 16
    (a) For the complex [Fe(H2O)6]3+, write the hybridization, magnetic character and spin of the complex. (At, number: Fe = 26)

    (b) Draw one of the geometrical isomers of the complex [Pt(en)2Cl2]2+ which is optically inactive. VIEW SOLUTION

  • Question 17
    An element crystallizes in a b.c.c. lattice with cell edge of 500pm. The density of the element is 7.5g cm–3. How many atoms are present in 300 g of the element? VIEW SOLUTION

  • Question 18
    (i) What is the role of Sulphur in the vulcanization of rubber?

    (ii) Identify the monomers in the following polymer :

    (iii) Arrange the following polymers in the increasing order of their intermolecular forces:
    Terylene, Polythene, Neoprene VIEW SOLUTION

  • Question 19

    For the first order thermal decomposition reaction, the following data were obtained:

    C2H5Cl(g) → C2H4(g) + HCl(g)

    Time/sec Total pressure/ atm
    0 0.30
    300 0.50

    Calculate the rate constant.
    (Given: log 2 = 0.301, log 3 = 0.4771, log 4 = 0.6021) VIEW SOLUTION

  • Question 20
    Give reasons for the following:

    (i) Aniline does not undergo Friedal-Crafts reaction.

    (ii) (CH3)2NH is more basic than (CH3)3N in an aqueous solution.

    (iii) Primary amines have higher boiling point than tertiary amines. VIEW SOLUTION

  • Question 21

    Define the following terms:

    (i) Lyophilic colloid
    (ii) Zeta potential
    (iii) Associated colloids


  • Question 22
    Calculate the boiling point of solution when 4 g of MgSO4 (M = 120 g mol–1) was dissolved in 100 g of water, assuming MgSO4 undergoes complete ionization.

    (Kb for water = 0.52 K kg mol–1) VIEW SOLUTION

  • Question 23

    Due to hectic and busy schedule, Mr. Singh started taking junk food in the lunch break and slowly became habitual of eating food irregularly to excel in his field. One during meeting he felt severe chest pain and fell down. Mr. Khanna a close friend of Mr. Singh took him to doctor immediately. The doctor diagnosed that Mr. Singhwas suffering from acidity and prescribed some medicines. Mr. Khanna advised hime to eat home made food and change his lifestyle by doing yoga, meditation and some physical exercise. Mr. Singh followed his friend's advice and after few days he started feeling better.

    After reading the above passage, answer the following:
    (i) What are the values (at least two) displayed by Mr. Khanna?
    (ii) What are antacids? Give one example.
    (iii) Would it be advisable to take antacids for a long period of time? Give reason.


  • Question 24
     (a) Write the structures of A and B in the following reactions:


    (b) Distinguish between:
         (i) C6H5 – COCH3 and C6H5 – CHO
         (ii) CH3COOH and HCOOH

    (c) Arrange the following in the increasing order of their boiling points:
         CH3CHO, CH3COOH, CH3CH2OH   

    (a) Write the chemical reaction involved in Wolff-Kishner reduction.

    (b) Arrange the following in the increasing order of their reactivity towards nucleophilic addition reaction:

         C6H5COCH3, CH3 – CHO, CH3COCH3

    (c) Why carboxylic acid does not give reactions of carbonyl group?

    (d) Write the product in the following reaction

         CH3 CH2 CH=CH-CH2CN  2.  H2O             1.  i-Bu2 AlH
    (e) A and B are two functional isomers of compound C3H6O. On heating with NaOH and I2, isomer B forms yellow precipitate of iodoform, whereas isomer A does not form any precipitate. Write the formulae of A and B. VIEW SOLUTION

  • Question 25
    (a) Calculate E°cell for the following reaction at 298 K:
    2Al(s) + 3Cu2+ (0.01 M) → 2Al3+ (0.01M) + 3Cu(s)
    Given: Ecell = 1.98V
    (b) Using the E° values of A and B, predict which is better for coating the surface of iron [E°(Fe2+/Fe) = –0.44V] to prevent corrosion and why?
    Given: E°(A2+/A) = –2.37V : E° (B2+/B) = –0.14V

    (a) The conductivity of 0.001 mol L–1 solution of CH3COOH is 3.905 × 10–5 S cm–1. Calculate its molar conductivity and degree of dissociation (α).
    Given λ0 (H+) = 349.6 S cm2 mol–1 and λ0 (CH3COO) = 40.9 S cm2 mol–1

    (b) Define electrochemical cell. What happens if external potential applied becomes greater than  E°cell of electrochemical cell? VIEW SOLUTION

  • Question 26
    (a) Account for the following:

    (i) Mn shows the highest oxidation state of +7 with oxygen but with fluorine, it shows the highest oxidation state of + 4.

    (ii) Cr2+ is a strong reducing agent.
    (iii) Cu2+ salts are coloured, while Zn2+ salts are white.

    (b) Complete the following equations:

    (i) 2MnO2+4KOH+O2         
    (ii) Cr2O72-+14H++6I-      

    The elements of 3d transition series are given as:
    Sc Ti V Cr Mn Fe Co Ni Cu Zn

    Answer the following:

    (i) Write the element which shows maximum number of oxidation states. Give reason.
    (ii) Which element has the highest m.p?
    (iii) Which element shows only + 3 oxidation state?
    (iv) Which element is a strong oxidizing agent in + 3 oxidation state and why? VIEW SOLUTION
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