Gujarat Board Class 12 Chemistry Sample Papers 2010

Class – XII
Subject – Chemistry


TIME: 2HR 30 MIN.                                    MM 75
General Instructions:

1)Although electron gain enthalpy of fluorine is less negative as compared to chlorine, fluorine is a stronger oxidizing agent than chlorine .Why?

2)      Explain the terms with examples:-     
             a) Gel                    b) Aersol                 c) Hydrosol.

3)The decomposition of NH3 on platinum surface is zero order reaction. What are the rates of production of nitrogen and hydrogen if k=2.5 X10-4 mol-1L s-1?

4) How will you distinguish the species in each of the following pairs:

(a)    CCl4 and CHCl3

(b)   Benzaldehyde and acetaldehyde

4)      Write the mechanism of free radical polymerization of an alkene?

5)      (a) Pick out the odd one amongst the following on the basis of  their  medicinal properties. Morphine, Serotonin, Codeine, Heroin.
        (b)    Give an example each of biodegradable and non- biodegradable detergents?

7) Calculate at 250C the equilibrium constant for the reaction.
                    2 Fe3+ + Sn2+    --->      2Fe2+ + Sn4+
         Given that E0(Fe3+/Fe2+), Pt = 0.771 V and E0(Sn4+/Sn2+), Pt =0.150 V

8 ) Name one solid which shows both Frenkel and Schottky defects together.

9) What is the difference between quartz and glass?

10) Write ionization isomer of the complex:        [CoCO3(NH3)5]Cl

11) Define ligand. Give one example.

12) Which method of refining is generally used when metal of high degree of purity is needed?
13) Why does R3P=O exists but R3N=O does not?     

14) (i) why copper matte is put in silica lined convertor?
     (ii). What is the role of cryolite in the metallurgy of aluminium ?

15) Why is zinc and not copper used for the recovery of metallic silver from its cyanide complex?

16) Explain the following:
(i)What problem arises in using alitame as artificial sweetener?
(ii)Cimetidine and Ranitidine are better antacids than sodium bicarbonate or magnesium hydroxide.

17) Explain:
(i)                 ZnO is white but turns yellow on heating and becomes highly conducting.
(ii)               CdCl2 will induce Schottky defect when introduced to AgCl crystal.
(iii)             Define Piezoelectricity.
(iv)             Why is Frenkel defect not found in pure alkali metal halides?
(v)               How does density of crystals change due to Schottky defect?

18) Silver crystallizes in fcc lattice. If edge length of the cell is 4.077 X10-8 cm and density is 10.5 g/cm3. Calculate the atomic mass of silver.  

19) Calculate the mass of a non volatile solute having molar mass 40g mol-1, which should be dissolved in 114g octane to reduce its vapour pressure to 80%.

20) Account for the following.
(i) Ethylene glycol is added to water in a car radiator when the car goes to a hill station.
(ii) Cut fruits after long exposure should not be consumed without adding sugar.

21) Silver forms face centred cubic structure. Its density is 10.65 g cm-3. Calculate the radius of silver atom. [Ag = 108.0 g mol-1; NA = 6.02 x 1023 mol-1]

22) (a) La(OH)3 is more basic than Lu(OH)3. Explain.
        (b) What is the cause of Lanthanide contraction?

23) A compound formed by elements P and Q crystallizes in the cubic structure where the P atoms are at the corners of the cube and Q atoms are at the body centers. What is the simplest formula of the compound?