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Sample Paper of Chemistry 2014 for class 12, CBSE. Paper No.1

  
        
          

SAMPLE PAPER – 2014

CLASS – XII

SUBJECT – Chemistry

 

General Instruction:

  1. All questions are compulsory.

  2. Marks of each question are indicated against it.

  3. Questions number 1 to 8 are very short answer questions and carry 1 mark each.

  4. Questions numbers 9 to 18 are short answer questions and carry 2 marks each.

  5. Question numbers 19 to 27 are also short answer questions and carry three marks each.

  6. Question numbers 28 to 30 is long answer questions and carry five marks each.

  7. Use log tables if necessary. Use of Calculators are not allowed.

1.What is meant by the term peptization?                                             (1)

  1. What is the oxidation number of Ni in [Ni(CO)4]? (1)

3.Why are phenols are more acidic than alcohols?                               (1)
4.Ketones are less reactive than aldehydes in the nucleophilic addition

reaction . Justify.                                                                                (1)
5.Why does not aniline show Friedel Craft reaction?                            (1)
6.Name the type of bonding which stabilizes alpha helix structure in

proteins?                                                                                            (1)
7.What are elastomers?                                                                         (1)

  1. How do antiseptic differ from disinfectants? (1)
  2. Silver crystallizes in fcc lattice. If edge length of the cell is 4.00×10-8

cm and density is 10.5 g cm-3, calculate the atomic mass of silver. (2)
10.In terms of band model ,what is the difference between :

(a) conductor and insulator and (b) conductor and semiconductor. (2)
11.State Henry’s law and mention some of its important applications.  (2)

  1. Account for the following : (2)

(i) Alkaline medium inhibits the rusting of iron. (ii)Iron does not rust

even if zinc coating is broken in a galvanized iron pipe.
13.Give reason for each of the following:                                              (2)

(i)Transition elements have high enthalpy of atomization.

(ii) Size of trivalent lanthanide cations decrease with increase in the

atomic number.
14.Draw figure to show splitting of d-orbitals in an octahedral crystal

field?                                                                                                (2)

  1. Account for the following: (2)

a)Haloalkanes undergo nucleophilic substitutions while haloarenes undergo electrophilic substitution.

b)Haloalkanes react with KCN form alkylcyanides while isocyanides are formed with AgCN.
16.How the following conversions can be carried out?                          (2)

(i) Toluene to benzyl alcohol (ii)Ethanol to but-1-yne.
17.Write the names of the monomers of the following polymers and

classify them as addition or condensation polymers.                       (2)

  1. a). What problem arises in using alitame as artificial sweetener?

(b)Sleeping pills are recommended by doctors to the patients

suffering from sleeplessness but it is not advisable to take its doses

without consultation with doctor. Why?                                            (2)
19.Calculate the boiling point of 1M  KCl solution. Density of

solution=1.04g/cm3. Molar mass of KCl=74.5u  Kb=0.52K Kg mole-1. 

                   Assume KCl is 90% dissociated in aqueous solution.                           (3)
20.(a)Write the equations of the reactions involved at each electrode in a

mercury cell.                                                                                   (2)

(b) Why does the potential of a mercury cell remain constant?     (1)

OR           

a)Calculate the equilibrium constant and work done by the cell

Ni + Cu2+                        Ni2+ +Cu Given E0Ni2+/Ni = – 0.25V E0Cu2+/Cu =

0.34 V.                                                                                           (2)

  1. b) Write the équations of the reactions involved at each electrode

during the electrolysis of CuSO4(aq) using inert electrode.          (1)
21.Outline the principles of refining of the metals by the following methods:(3)

  1. a) Vapor phase refining b) Liquation c) Zone refining.

22.(i)Explain what is observed when: (3)

  1. an emulsion is subjection to centrifugation.
  2. direct current is passed through a colloidal sol.

(ii)Write a chemical equation showing the preparation of a positive

sol.

  1. Give the products and balance the following equations: (3)

(i)Ca3P2 +H2O

(ii) XeF6 +NaF

(iii)Cu + H2SO4 (conc)

  1. Account for the following:                                                        (3)
  2. a) Zn,Cd, and Hg are not considered as transition elements.
  3. b) Actinoid show variety of oxidation states.
  4. c) E0Mn3+/Mn2+ has higher positive value than E0 Cr3+/Cr2+(Atomic

number of Cr=24, and Mn=25)

  1. Account for the following:                                                          (3)
    a) Methanamine is less acidic than methanol.
  2. b) Tert. amines do not react with acid derivatives.
  3. c) Basic character of amines in vapor phase is 30amine>20amine>10

26.(a)Write the equations involved in the following reactions:                   (2)

(i)Reimer Tiemann Reaction and (ii) Kolbe’s Reaction.

(b)Write IUPAC name of the following compound:                                 (1)

C6H5-O-C2H5.
27(a)Write the reactions of glucose with (i) HI (ii)HNO3.                      (2)

(b)Discuss the amphoteric nature of amino acid with suitable

example.                                                                                          (1)

28.(a) A first order reaction has k=1.5×10-6 per second at 2400C. If the reaction is allowed to run for 10 hours, what percentage of the initial concentration would have changed to products? What is the half life period of this reaction?

(b)A 1st order reaction is 50% complete in 30 minutes at 270C and in

10 min. at 470C.Calculate

(i) rate constant for reaction at 270C and 470C.

(ii) energy of activation for the reaction.                                      (5)

OR

Two reactions i) Aà products ii) Bà products, follow first order kinetics. The rate of the reaction (i) is doubled when temperature is raised from 300K to 310K. The half life for this reaction at 310K is 30 minutes. At the same temperature B decomposes twice as fast as A. If the energy of activation for the reaction (ii) is half that of reaction (i), calculate the rate constant of reaction (ii) at 300K.  5

  1. Account for the following.

(i)  PH3 is a weaker base than NH3.

(ii) SF6 exists but SH6 does not.

(iii)ClF3 exists but FCl3 does not.

(iv) H3PO3 is diprotic acid.

(v) ICl is more reactive than I2.                                                                      (5)

OR

(a)Assign reason for the following

(i) Concentrated nitric acid turns yellow on exposure to sunlight.

(ii)The negative value of electron gain enthalpy of Fluorine is less than that of Chlorine. (iii)HI is a stronger acid than HF.

(iv)SF6 is used as a gaseous electrical insulator.

(v) pKa value of HOCl is higher than that of HClO2.

  1. (a)An organic compound (A) with the molecular formula C9H10O forms 2,4 –DNP derivative, reduces Tollen’s reagent to get(B).On vigorous oxidation it gives 1,2-benzene dicarboxylic acid. Give the structures of A and B.

(b)Convert

(i)  Acetophenone to 2-phenyl-2-butanol.

(ii) Propene to acetone.                                                                       (5)

OR

An organic compound (A) of molecular weight 140.5 has 68.32% carbon, 6.4% Hydrogen and 25.26% Chlorine. Hydrolysis of (A) with dilute acid gives compound (B). Compound (B) can be oxidized under mild conditions to compound (C) C8H8O. Compound (C) forms phenyl hydrazones (D) and gives a positive iodoform test. Deduce the structures of (A)to(D).                                         (5)

 

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