Surface Chemistry Quiz

1

The phenomenon of attracting and retaining molecules on the surface resulting in higher concentration is called:

Absorption Adsorption Sorption Occlusion

2

Which of the following is a surface phenomenon?

Absorption Adsorption Both Neither

3

The substance on whose surface adsorption occurs is called:

Adsorbate Adsorbent Absorbate Absorbent

4

When NH₃ gas is placed in contact with charcoal:

It is absorbed It is adsorbed Both occur Neither occurs

5

Adsorption is accompanied by:

Increase in enthalpy Decrease in enthalpy No change in enthalpy Increase in entropy

6

Which type of adsorption is irreversible?

Physisorption Chemisorption Both Neither

7

Heat of adsorption in physisorption is:

20-40 kJ/mol 50-400 kJ/mol 400-800 kJ/mol >800 kJ/mol

8

Chemisorption forms:

Multimolecular layers Monomolecular layer No layers Bilayer

9

Which gas is adsorbed to a greater extent?

H₂ N₂ CO₂ He

10

The extent of adsorption increases with:

Decrease in surface area Increase in temperature Increase in pressure Decrease in pressure

11

Freundlich adsorption isotherm is:

x/m = k p x/m = k p^{1/n} x/m = k / p x/m = k p^n

12

At low pressure, extent of adsorption is proportional to:

1/p p p² 1/p²

13

Physisorption isobar shows:

Increase with temperature Decrease with temperature No change First increase then decrease

14

Positive adsorption occurs when:

Concentration on surface < bulk Concentration on surface > bulk Equal concentration No adsorption

15

Which has higher activation energy?

Physisorption Chemisorption Both same Neither

16

Adsorption of gases on metals is called:

Absorption Sorption Occlusion Desorption

17

Which shows negative adsorption?

Conc. KCl on charcoal Dilute KCl on charcoal NH₃ on charcoal CO₂ on charcoal

18

Chemisorption is:

Non-specific Highly specific Reversible at low temp Multilayer

19

In Freundlich isotherm, n is always:

Less than 1 Equal to 1 Greater than 1 Zero

20

Adsorption is a spontaneous process because:

ΔH positive ΔS positive ΔG negative ΔG positive