CBSE Chemistry Test Paper

1. Differentiate between ore and mineral? (1)

2. Nitrogen is inert compared to phosphorous why? (1)

3. Give an example of shape selective catalyst? (1)

4. What are aerosols give example. (1)

5. Why do Zr and Hf exhibit similar properties ? (1)

6. Assign a reason (2)

a)Ammonia is stronger base than phosphine

b)Catenation tendency of Sulphur is more than Oxygen .

7. Complete the eqn (2)

(i)Ca3P2 + H2O → (i) Cu2+ + NH3

8.Explain the role of (2)

a)Cryolite in the electrolytic reduction of alumina b)CO in the purification of Ni

9.What is the role of stabiliser and depressant in forth floatation process? (2)

10.What is te difference between multimolecular and macromolecular colloid ? Give example of each. (2)

11. Explain what is observed when (3)

a.KCl , an electrolyte is added to hydrated ferric oxide sol b.an electric current is passed through a colloidal solution c.a beam of light is passed through a colloidal solution

12.Describe how the following changes are brought about. (3)

a.Pig iron into Steel. b.Zinc Oxide into matalic zinc. c.Impure titanium into pure titanium.

OR

Describe the role of

a.NaCN in the extraction of gold from gold ore . b.SiO2 in the extraction of Cu from copper matte.

c.Iodine in the refining of zirconium..

13.Draw the structure of the following. (3)

a.H2S2O7 . b.H2SO4. c.H3PO4

 

14. Explain the following by giving reason

a.Out of C and CO which is a better reducing agent for ZnO (3)

b.Reduction of metallic oxide easier if the metal formed in liquid state at the temperature of

reduction.

c.Cr2O3+2Al Al2O3 + 2Cr ∆G(-) =-421 KJ is thermodynamically feasible as it is apparent from

the Gibbs energy value. Why does it not take place at room temperature?

15. What is adsorption isotherm ?Explain freundlich adsorption isotherm with the help of graph (3)

16. a. Out of the ions Cu2+ ,Co2+,Tc4+ which one will be

colourless in aqueous solution and why? (5)

[At. Number of Cu=29,CO=27,Ti =22]

b.If each one of these species is in turn placed in a magnetic field how will it respond and why?

c. Why is Mn2+ more stable than Mn3+

d.Transition metals have high melting and boiling points?

e. Transition elements have great tendency for complex formation

OR

a.There is a gradual decrese in the atom size of transition elements in a series with

increasing atomic numbers

b.Lanthum and lutetium donot show colouration in solutions

(At no La =57 ,Lu= 71)

c.The enthalpies of atomisation of transition metals are quite high

d.Among the di valent cations in the first series of transition elements manganese exibit

maximum paramagnatisam.

e. Cu+ ion is not known in aqueous solution.

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