CBSE Question Paper 2010 class 12 Chemistry

1. All questions are compulsory.
2. Marks for each question are indicated against it.
3. Question numbers 1 to 8 are very short-answer questions, carrying 1 mark each. Answer these in one word or about one sentence each.
4. Question numbers 9 to 18 are short-answer questions, carrying 2 marks each. Answer these in about 30 words each.
5. Question numbers 19 to 27 are short-answer questions of 3 marks each. Answer these in about 40 words each.
6. Question numbers 28 to 30 are long-answer questions of 5 marks each. Answer these in about 70 words each.
7. Use Log Tables, if necessary Use of calculators is not permitted.

1. Write a feature which will distinguish a metallic solid from an ionic solid. [1]

2. Define ‘order of a reaction’. [1]

3. What is an emulsion? [1]

4. Why does  dimerise? [1]

5. Give an example of linkage isomerism. [1]

6. A solution of  hydrolyses  Which one of these is more easily hydrolysed? [1]

7. Draw the structural formula of I-phenylpropan-l-one molecule. [1]

8. Give the IUPAC name of  [1]

9. Non-ideal solutions exhibit either positive or negative deviations from Raoult’s law. What are these deviations and why are they caused? Explain with one example for each type. [2]

10. A reaction is of first order in reactant A and of second order in reactant B. How is the rate of this reaction affected when (i) the concentration of B alone is increased to three times (ii) the concentrations of A as well as B are doubled? [2]

11. The rate constant for a reaction of zero order in  How long will it take for the initial concentration of A to fall from  [2]

12. Draw the structures of white phosphorus and red phosphorus. Which one of these two types of phosphorus is more reactive and why? [2]

13. Explain the following observations:

(i) Generally, there is an increase in density of elements from titanium (Z = 22) to copper (Z = 29) in the first series of transition elements.

(ii) Transition elements and their compounds are generally found to be good catalysts in chemical reactions. [2]

14. Name the following coordination compounds according to IUPAC system of nomenclature: [2]

15. Illustrate the following reactions giving a chemical equation for each:

(i) Kolbe’s reaction,

(ii) Williamson synthesis. [2]

16. How are the following conversions carried out?

(i) Benzyl chloride to benzyl alcohol,

(ii) Methyl magnesium bromide to  [2]

17. Explain the following terms:

(i) Invert sugar

(ii) Polypeptides

OR

Name the products of hydrolysis of sucrose. Why is sucrose not a reducing sugar? [2]

18. What are essential and non-essential amino acids in human food? Give one example of each type. [2]

19. The well-known mineral fluorite is chemically calcium fluoride. It is known that in one unit cell of this mineral there are  and that  are arranged in a fcc lattice. The  fill all the tetrahedral holes in the face centred cubic lattice of . The edge of the unit cell is  in length. The density of the solid is  Use this information to calculate Avogadro’s number  [3]

20. A solution prepared by dissolving  of oil of winter green (methyl salicylate) in  of benzene has a boiling point of  Determine the molar mass of this compound.  [3]

21. What is the difference between multi molecular and macromolecular colloids? Give one example of each type. How are associated colloids different from these two types of colloids? [3]

22. Describe how the following changes are brought about:

(i) Pig iron into steel.

(ii) Zinc oxide into metallic zinc.

(iii) Impure titanium into pure titanium. [3]

OR

Describe the role of

(i)  in the extraction of gold from gold are.

(ii)  in the extraction of copper from copper matte.

(iii) Iodine in the refining of zirconium.

Write chemical equations for the involved reactions.

23. How would you account for the following?

(i) The atomic radii of the metals of the third  of transition elements are virtually the same as those of the corresponding members of the second

(ii) The  value for the  couple is much more positive than that for  couple or  couple.

(iii) The highest oxidation state of a metal is exhibited in its oxide or fluoride. [3]

24. (i) State one use each of DDT and iodoform.

(ii) Which compound in the following couples will react faster in  displacement and why?

(a) 1-Bromopentane or 2-bromopentane

(b) 1-Bromo-2-methylbutane or 2-bromo-2-methylbutane. [3]

25. In the following cases rearrange the compounds as directed: [3]

(i) In an increasing order of basic strength:

(ii) In a decreasing order of basic strength:

Aniline, p-nitroaniline and p-toluidine

(iii) In an increasing order of  values:

26. Give one example each of

(i) addition polymers,

(ii) condensation polymers,

(iii) copolymers. [3]

27. What are analgesic medicines? How are they classified and when are they commonly recommended for use? [3]

28. (a) State Kohlrausch law of independent migration of ions. Write an expression for the molar conductivity of acetic acid at infinite dilution according to Kohlrausch law.

(b) Calculate  for acetic acid.

Given that

 [5]

OR

(a) Write the anode and cathode reactions and the overall reaction occurring in a lead storage battery.

(b) A copper-silver cell is set up. The copper ion concentration is  The concentration of silver ion is not known. The cell potential when measured was  Determine the concentration of silver ions in the cell.  [5]

29. (a) Complete the following chemical equations:

(b) How would you account for the following?

(i) The value of electron gain enthalpy with negative sign for sulphur is higher than that for oxygen.

(ii)  is an exothermic compound but  is endothermic compound.

(iii)  molecule has a T-shaped structure and not a trigonal planar one. [5]

OR

(a) Complete the following chemical reaction equations:

(b) Explain the following observations giving appropriate reasons:

(i) The stability of +5 oxidation state decreases down the group in group 15 of the periodic table.

(ii) Solid phosphorus pentachloride behaves as an ionic compound.

(iii) Halogens are strong oxidizing agents. [5]

30. (a) Explain the mechanism of a nucleophilic attack on the carbonyl group of an alciehyde or a ketone.

(b) An organic compound  was hydrolysed with dilute sulphuric acid to give a carboxylic acid (B) and an alcohol (C). Oxidation of (C) with chromic acid also produced (B). On dehydration  Write the equations for the reactions involved. [5]

OR

(a) Give chemical tests to distinguish between the following pairs of compounds:

(i) Ethanal and Propanal

(ii) Phenol and Benzoic acid

(b) How will you bring about the following conversions? 5

(i) Benzoic acid to benzaldehyde

(ii) Ethanal to but-2-enal

(iii) Propanone to propane

Give complete reaction in each case.

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