Chemistry Sample paper1

 Ist Pre -Board Examination 2008-09

CLASS – XII

Subject – Chemistry

 

       Time: Three Hours                                                                   Max.Marks: 70

 

1. All questions are compulsory.

2. Question nos. 1 to 8 are very short answer questions and carry 1 mark each.

3. Question nos. 9 to 18 are short answer questions and carry 2 marks each.

4. Question nos. 19 to 27 are also short answer questions and carry 3 marks each

5. Question nos. 28 to 30 are long answer questions and carry 5 marks each

6. Use log tables if necessary, use of calculators is not allowed.

  1. when a crystal of NaCl is heated in Na vapour it acquires a yellow Colour. This is due to which defect?                                                                                              1
  2. Two liquids A and B boil at 1350 C and 1850  C respectively. Which of them has higher vapour pressure at 800 C?                                                                   1
  3.   Identify X  :       X +H2   pd-BaSO4        C6H5(CH2CHO)                                       1
  4. What happen when a freshly prepared ferric hydroxide is shaken with ferric chloride solution? Name the process                                                                           1
  5. Although thermodynamically feasible, in practice, Mg metal is not used for the reduction of alumina in the metallurgy of Al  why?                                     1
  6. Which amongst the following is strongest oxidizing agent   

               ClO4 ,BrO 4  ,IO4                                                                                        1

       7.  Sulphur   in vapor state exhibits Para magnetism, why?                                    1

        8. p-Dichlorobenzene has higher m.p and solubility than ortho and meta isomer .why?                                                                                                            1

9. A reaction is carried out at two different initial concentrations of reactant. The initial concentrations are 1 mol L-1 and 2 mol L-1. The half life values obtained were 20 min and 40 min respectively. What is the order of the reaction?                                                                                                               2

  1. Assuming complete dissociation, calculate the freezing point of a solution prepared by dissolving 6 g of glaubers salt(Na 2 SO4.10 H2O) in 0.100 kg of water.(kf = 1.86 k kg mol-1)                                                                                            2

11.    State Henry`s Law and mention some applications of Henry`s constant.       2

                                                    Or

Molarity or molality, which is the best method to express concentration of a solution?             Why?                                                                                                 

12.    (i)Primary amines  have higher boiling point than tertiary amines. Why?

(ii)Ammonolysis of alkyl halide doesnot give a corresponding pure amine .Expline ?                                                                                                           2

13. C6H5NO2—-Fe/HCl—-àA—NaNO2+HCl—–àB—-H2O/H+àC                                2                        Identify A,B,C

      14.Define(i)Peptide bond (ii) Denaturation as related to proteins                          2

15.Write the diseases caused by the deficiency of Vitamin A,C,D & E                  2

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