#### 12th Standard Chemistry English Medium Surface Chemistry Reduced Syllabus Important Questions 2021

12th Standard

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Chemistry

Time : 01:00:00 Hrs
Total Marks : 100

Multiple Choice Questions

15 x 1 = 15
1. For Freundlich isotherm a graph of log $\frac{x}{m}$ is plotted against log P. The slope of the line and its y – axis intercept respectively corresponds to

(a)

$\frac{1}{n}$ ,K

(b)

log$\frac{1}{n}$ ,K

(c)

$\frac{1}{n}$ ,logK

(d)

log $\frac{1}{n}$ ,log K

2. Which one of the following characteristics are associated with adsorption?

(a)

$\Delta$G and $\Delta$H are negative but $\Delta$S is positive

(b)

$\Delta$G and $\Delta$S are negative but $\Delta$H is positive

(c)

$\Delta$G is negative but $\Delta$H and $\Delta$S are positive

(d)

$\Delta$G,$\Delta$H and $\Delta$S all are negative.

3. Which one of the following is an example for homogeneous catalysis?

(a)

manufacture of ammonia by Haber’s process

(b)

manufacture of sulphuric acid by contact process

(c)

hydrogenation of oil

(d)

Hydrolysis of sucrose in presence of all HCl

4. Which among the following true regarding adsorption?
(i) Adsorption is a spontaneous process
(ii) Adsorption is always accompanied by increase in free energy.
(iii) Adsorption is an endothermic process
(iv) Adsorption can occur in all interfacial surfaces.

(a)

only (ii)

(b)

(ii) and (iii)

(c)

only (i)

(d)

(i) and (iv)

5. According to Freundlich adsorption isotherm,

(a)

$\frac { x }{ m } =kp$

(b)

$\frac { m }{ x } ={ (kp) }^{ \frac { 1 }{ n } }$

(c)

$\frac { x }{ m } ={ kp }^{ \frac { 1 }{ n } }$

(d)

$\\ \\ \frac { x }{ m } =\frac { k }{ { p }^{ \frac { 1 }{ n } } }$

6. Which of the following is true regarding Freundlich adsorption isotherm equation?

(a)

Purely empirical

(b)

Valid only over a limited pressure range

(c)

The value of constants k and n varies with temperature

(d)

All the above

(a)

decrease in free energy

(b)

increase in free energy

(c)

increase in entropy

(d)

both (b) and (c)

8. Which among the following is an example of absorption?

(a)

Water on calcium chloride

(b)

Water on silica gel

(c)

Ammonia gas on charcoal

(d)

Hydrogen on finely divided nickel

9. Which among the following is not correct with regards to enzyme catalysis?

(a)

The rate of enzyme catalysisvaries with pH.

(b)

Enzyme catalysisis highly specific in nature

(c)

Catalytic activity of enzymes is increased by co-enzymes

(d)

Enzymes cannot be inhibited

10. In case of physical adsorption, there is desorption when

(a)

temperature increases

(b)

temperature decreases

(c)

pressure increases

(d)

concentration increases

11. When the operation force between the absorbent and adsorbate is weak Vander waal's force, then it is called

(a)

(b)

(c)

(d)

both (a) and (c)

12. The decomposition of hydrogen peroxide in the presence of colloidal platinum is a/an

(a)

positivecatalysis

(b)

negativecatalysis

(c)

auto-catalysis

(d)

induced catalysis

13. Variation of adsorption at constant pressure is_______

(a)

isobar

(b)

isotherm

(c)

isochor

(d)

isomer

14. In auto catalysis____________ acts as catalyst

(a)

reactant

(b)

produc

(c)

both

(d)

none

15. Silica gel is utilised for the ________of the number of gases.

(a)

(b)

absorption

(c)

desorption

(d)

all of these

16. 2 Marks

10 x 2 = 20
17. What do you mean by positive and negative adsorption?

19. What are limitations of Freundlich adsorption isotherm?

20. What are the concepts of catalysis that intermediate compound formation theory throws light on?

21. Why are colloids purified?

22. What is the formula for Ziegler - Natta catalyst?

23. What are the two types of catalysis?

24. What are lyophilic colloids? Give examples.

25. Write the Freundlich adsorption isotherm?

26. Adsorption of a gas on the surface of solid is generally accompanied by decrease in entropy. Still it is a spontaneous process. Explain.

27. 3 Marks

10 x 3 = 30
28. Why are lyophillic colloidal sols are more stable than lyophobilc colloidal sol.

29. What are the factors which influence the adsorption of a gas on a solid?

30. What do you mean by activity and selectivity of catalyst?

31. Give any three application of adsorption.

32. Write a note.
(i) Positive catalyst
(ii) Negative catalyst

33. Write a note on auto catalysis?

34. Give three examples of enzyme catalyzed reactions.

35. Explain the advantages of using nano catalyst.

36. Name various techniques by which a colloid can be deemulsified.

37. Write the optical properties of colloids with diagram.

38. 5 Marks

7 x 5 = 35
39. Why is desorption important for a substance to act as good catalyst?

40. Describe adsorption theory of catalysis

41. Explain the factors affecting adsorption.

42. Write a note on Freundlich adsorption isotherm.

43. Give the special characteristics of enzyme catalysed reactions.

44. Write a note on phase transfer catalysis.

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