CBSE 12th Board Sample Paper Chemistry

Central Board of Secondary Education (CBSE)

Sample Paper – 2012
Class – XII
Subject – Chemistry

 1.  Why are crystalline solids anisotropic in nature?

2.  What is the dislocation defect better known as? What is its effect on density?

3.  What is the order of radioactive decay?

4.  What will be the effect of temperature on rate constant?

5.  What happens when White Phosphorus is heated with conc. NaOH solution in an inert atmosphere?

6.  Write the structure of 3-Bromo-2-methylpropene.

7.Write any one method of preparing benzaldehyde from Toluene.

8.   Name the four bases present in DNA.

9.  Silver crystallizes in an FCC lattice. The edge length of its unit cell is 4.077 x 10-8 cm and its density is 10.5 g/cm3. Calculate the atomic mass of silver?

10. Express the relation among the cell constant, the resistance of the solution in the cell and the conductivity of a solution related to its molar conductivity?

11.Statetwo features of chemical adsorption which are not found with physical adsorption?

12. Explain the role of the following:


i)                    Activated charcoal in gas mask.

ii)                    Zeolites in petroleum industry.


 Explain the following terms with suitable examples:


i)                    Selectivity of a catalyst.

ii)                    Peptization


13.  Give reasons:

i)                     PH3 is a weaker base than NH3

ii)                    H2O is a liquid while H2S is a gas at room temperature.

14.  What is the difference in the structures of White phosphorous and Red phosphorous? How does it effect their melting point?                                                                                                                               [2]

15.  i) How can be differentiate by chemical test between Butan-2-ol and 2-methylpropan-2-ol.

ii) Boiling point of Ethers are lower than their isomeric alcohols.Explain

16. o-Nitrophenol is steam volatile while p-Nitrophenol is not .Explain with diagram.

17.  Account for the following (any two) :

i)                    Ethylamine is soluble in water whereas Aniline is not.

ii)                  Diazonium salts of aromatic amines are more stable than those of Aliphatic amines .

iii)                pKb of aniline is more than that of methyl amine.

18.   Write short notes on the following :


i)                    Carbylamine reaction

ii)                  Gabriel phthalimide synthesis.

19. Calculate the cell emf and ΔG for the cell reaction at 250 C for the cell:

Zn(s)| Zn2+ (0.0004 M) || Cd2+ (0.2 M)| Cd (s)

E0 values at 250C , Zn2+/ Zn = -0.763 V, Cd2+ |Cd = -0.403 V

F = 96500 C mol-1, R = 8.314 J K-1 mol-1.


Sample Paper / model Test Paper for CBSE 12th 2012

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