Surface Chemistry Test

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Surface Chemistry Test - 41

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Weekly Quiz Competition

Question 1
1 / -0

Freshly prepared precipitate sometimes gets converted to colloidal solution by:

A
coagulation

B
electrolysis

C
diffusion

D
peptisation
Solution
- Peptization may be defined as the process of converting a precipitate into colloidal sol by shaking it with dispersion medium in the presence of a small amount of electrolyte.
- During peptization, the precipitate adsorbs one of the ions of the electrolyte on its surface. This causes the development of a positive or negative charge on precipitates, which ultimately break up into smaller particles of the size of a colloid.
- Hence, freshly prepared precipitate sometimes gets converted to colloidal solution by peptization.
Question 2
1 / -0

In which of the following reactions heterogeneous catalysis is involved?
(I) $$2SO_{2}$$ + $$O_{2}$$ $$\overset{V_{2}O_{5}}{\longrightarrow}$$ $$2SO_{3}$$
(II) $$2SO_{2}$$ + $$O_{2}$$ $$\overset{NO_{(g)}}{\longrightarrow}$$ $$2SO_{3}$$
(III) $$2N_{2} + 3H_{2}$$ $$\overset{Fe}{\longrightarrow}$$ $$2NH_{3}$$
(IV) $$CH_{3}COOCH_{3}$$ + $$H_{2}O$$ $$\overset{HCl_{(aq)}}{\longrightarrow}$$ $$CH_{3}COOH$$ + $$CH_{3}OH$$

A
(I), (III)

B
(II), (III), (IV)

C
(I), (II), (III)

D
(IV)

Solution

When reacting species and products are in the same phase that of catalyst is called homogeneous catalysis. When reacting species and products are in a different phase that of catalyst is called heterogeneous catalysis.

Reaction (I) and (III) are heterogeneous catalysis since reacting species and products are in the gas phase and catalyst is in the solid phase.

So, the correct option is A.
Question 3
1 / -0

The role of a catalyst is to change _______.

A
the Gibbs energy of reaction

B
enthalpy of reaction

C
activation energy of reaction

D
equilibrium constant

Solution

Catalyst is used to decrease the activation energy so as to increase the rate of reaction.
option 'c' is correct.
Question 4
1 / -0

Which of the following phenomenon is applicable to the process shown in the figure?

A
Absorption

B
Adsorption

C
Coagulation

D
Emulsification

Solution

When the aqueous solution of raw sugar is passed over the animal charcoal, the charcoal adsorbs all the colouring material and hence raw sugar solution becomes colourless.
Question 5
1 / -0

In the presence of a catalyst, the heat evolved or absorbed during the reaction:

A
increaases

B
decreases

C
remains unchanged

D
may increase or decrease

Solution

Change in enthalpy of the reaction doesn't alter with catalyst.
Question 6
1 / -0

Which of the following is an example of absorption?

A
Water on silica gel

B
Water on calcium chloride

C
Hydrogen on finely divided nickel

D
Oxygen on metal surface

Solution

Water on calcium chloride. Absorption means penetration of adsorbate molecules into the bulk of the adsorbent. When water is spread over calcium chloride, water get penetrate into bulk of the calcium chloride.
Question 7
1 / -0

Which of the following will form a reversible sol?

A
Gold sol

B
Sulphur sol

C
Rubber sol

D
Arsenous sulphide sol

Solution

Reversible sols are such that if two constituents of the sol are separated by any means (such as evaporation), then the sol can be prepared again by simply mixing the dispersion medium with the dispersion phase and shaking the mixture. Example: gum, gelatin, starch, rubber.
Question 8
1 / -0

Entropy change $$(\Delta S)$$ for adsorption:

A
negative

B
positive

C
zero

D
cannot be said

Solution

In adsorption, Process is exothermic and randomness of molecule decrease. Hence $$\bigtriangleup S=$$ Negative
Question 9
1 / -0

Alcohols can be converted to various types of gasoline(period) by shape-selective catalyst.

A
Maltase

B
ZSM-$$5$$

C
Lindlar's catalyst

D
Ziegler Natta catalyst

Solution

Zeolite catalyst known as ZSM-5 converts alcohols to gasoline. The alcohol is dehydrated in the cavities and the hydrocarbons are formed.
Question 10
1 / -0

Which of the following gases can be adsorbed in more proportion?

A
$$N_{2}$$

B
$$CO_{2}$$

C
$$O_{2}$$

D
$$H_{2}$$

Solution

In general, easily liquefiable gases e.g., $$CO_2, NH_3, Cl_2, SO_2$$ etc. are adsorbed to a greater extent than the elemental gases e.g. $$H_2, O_2, N_2, He$$ etc.
thus option B is correct

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Surface Chemistry Test - 41

Result

Surface Chemistry Test - 41

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Question 1

coagulation

electrolysis

diffusion

peptisation

Solution

Question 2

(I), (III)

(II), (III), (IV)

(I), (II), (III)

(IV)

Solution

Question 3

the Gibbs energy of reaction

enthalpy of reaction

activation energy of reaction

equilibrium constant

Solution

Question 4

Absorption

Adsorption

Coagulation

Emulsification

Solution

Question 5

increaases

decreases

remains unchanged

may increase or decrease

Solution

Question 6

Water on silica gel

Water on calcium chloride

Hydrogen on finely divided nickel

Oxygen on metal surface

Solution

Question 7

Gold sol

Sulphur sol

Rubber sol

Arsenous sulphide sol

Solution

Question 8

negative

positive

zero

cannot be said

Solution

Question 9

Maltase

ZSM-$$5$$

Lindlar's catalyst

Ziegler Natta catalyst

Solution

Question 10

$$N_{2}$$

$$CO_{2}$$

$$O_{2}$$

$$H_{2}$$

Solution

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