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