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#### Surface Chemistry Model Question Paper

12th Standard EM

Reg.No. :
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Chemistry

Time : 01:00:00 Hrs
Total Marks : 45
9 x 1 = 9
1. Hair cream is

(a)

gel

(b)

emulsion

(c)

solid sol

(d)

sol.

2. The coagulation values in millimoles per litre of the electrolytes used for the coagulation of AS2S3 are given below
(I) (NaCl)=52 (II) ((BaCl2)=0.69 (III) (MgSO4)=0.22
The correct order of their coagulating power is

(a)

III > II > I

(b)

I > II > III

(c)

I > III > II

(d)

II > III>I

3. Which among the following does not affect adsorption?

(a)

(b)

catalyst

(c)

temperature

(d)

pressure

4. Which one of the following is correctly matched?

(a)

Emulsion - Mayonnaise

(b)

Foam - Cream

(c)

Solid aerosol - Fog

(d)

Solid sol - Pumice stone

5. The phenomenon of scattering of light by the sol particles is called

(a)

tyndall effect

(b)

electrophoresis

(c)

cataphoresis

(d)

dialysis

6. Tyndall effect is a _____property of colloidal particles.

(a)

optical

(b)

kinetic

(c)

electrical

(d)

eletromc

7. In W/O system, the dispersion medium is_______

(a)

water

(b)

benzene

(c)

alcohol

(d)

oil

8. The platinum catalyst used in the oxidation of SO2 by contact process is poisoned by

(a)

As2O3

(b)

V2O5

(c)

Fe2O3

(d)

CuCl2

9. Electrophoresis is a_________property of a colloid.

(a)

Optical

(b)

Kinetic

(c)

Electrical

(d)

Magnetic

10. 1 x 1 = 1
11. Pick out the correct statement with respect of lyophillic sol.
a) They are less stable
b) They will not be precipitated easily
c) There is no definite attractive force existing between the dispersion medium and dispersed phase
d) They are called irreversible sols.

()

They will not be precipitated easily

12. 2 x 2 = 4
13. Assertion: Gases such as SO2' NH3• HCI are easily adsorbed.
Reason : Adsorption is a surface phenomenon
a) (A) and (R) are true and (R) is the correct explanation of (A)
b) Both (A) and (R) are true but (R) does not explain (A)
c) (A) is true but (R) is false
d) Both (A) and (R) are false

14. Assertion: Colloidal solutions show colligative properties.
Reason : Colloidal particles are larger in size.
a) (A) and (R) are true and (R) is the correct explanation of (A)
b) Both (A) and (R) are true but (R) does not explain (A)
c) (A) is true but (R) is false
d) Both (A) and (R) are false

15. 1 x 2 = 2
16. Pick out the wrong statement regarding physical adsorption.
a) It is reversible
b) It depends on the nature of the gas
c) It is due to Vanderwall's force
d) Heat of adsorption is large

17. 4 x 2 = 8
18. The mechanism of Fridel crafts reaction is given below
${ C }_{ 6 }{ H }_{ 5 }+{ { CH }_{ 3 }Cl\overset { anhydrous\\ \quad \quad \quad { Alcl }_{ 3 } }{ \longrightarrow } }{ C }_{ 6 }{ H }_{ 5 }{ CH }_{ 3 }+HCl$

19. Write a note on dialysis.

20. What is Tyndall effect?

21. Why the sun looks red at the time of setting? Explain on the basis of colloidal properties.

22. 2 x 3 = 6
23. Give an example for a reaction catalysed by nano particles

24. Explain the preparation of colloidal platinum by Bredig arc method.

25. 3 x 5 = 15
26. Explain any one method for coagulation

27. Give the special characteristics of enzyme catalysed reactions.

28. Write any five applications of colloids in day - to day life.