Assignment No – 2
Surface Chemistry

ASSERTION REASON TYPE:
A statement of assertion is followed by a statement of reason. Mark the correct choice from the options given below:
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Both assertion and reason are false.
1. Assertion: A colloidal sol scatters light but a true solution does not.      
Reason: The particles in a colloidal sol move slowly than in a true solution.

2. Assertion: Activation energy for both the forward and backward reactions is lowered to the same extent by a catalyst.
Reason: A reaction cannot become fast by itself unless a catalyst is added.

3. Assertion: Hydrolysis of ester is an example of auto - catalytic reaction.
Reason: A catalyst speeds up the process without participating in the mechanism.

4. Assertion: Hydrated ferric oxide can be easily coagulated by sodium phosphate in comparison to KCl.
Reason: Phosphate ions has higher negative charge than chloride ions. Hence, they are more effective for coagulation.

5. Assertion: During preparation of ice - cream, gelatin is added in it.
Reason: Ice -creams are emulsions which get stabilised by gelatin as it acts as an emulsifying agent.

ONE - WORD ANSWER
Que 6. Which phenomenon is responsible for formation of delta?

Que 7. Name a cheap material useful for causing artificial rain?

SHORT ANSWER QUESTIONS
Que 8. Explain what is observed
(i)              When a beam of light is passed through a colloidal soln.
(ii)            Electric current is passed through a colloidal soln.

Que 9. Explain:
(i)              Electrophoresis (ii) Coagulation

Que 10. What are micelles? Give an example of a miceller system.

Que 11. (i) Why is ferric chloride preferred over potassium chloride in the case of a cut leading to bleeding?
(ii) Why is desorption important for a substance to act as a good catalyst?