Surface Chemistry Test

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Surface Chemistry Test - 36

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Weekly Quiz Competition

Question 1
1 / -0

Which of the following statement is incorrect for physical adsorption ?

A
It is instantaneous

B
Monomolecular layer forms on the adsorbent

C
Less activation energy is required for it

D
Generally it results at low temperature and adsorption decreases with increase in temperature

Solution

Physical adsorption Is an instantaneous process in which van der Waals' forces exist between the adsorbate and adsorbent. Thus, an activation energy of such adsorption is low and it results in the formation of multimolecular layer (more than one molecule thick).

Physisorption occurs at low temperature and decreases with rising in temperature.

Hence, option B is correct.
Question 2
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Which of the following characteristics is not correct for physical adsorption ?

A
Adsorption is spontaneous

B
$$\Delta \, H$$ and $$\Delta \, S$$ are negative

C
It is reversible in nature

D
Degree of adsorption increases with temperature

Solution

Physical adsorption is exothermic in nature. So the rate of Physical adsorption decreases with an increase in temperature.
Question 3
1 / -0

Which one of the following is an example for homogenous catalysis?

A
Manufacture of sulphuric acid by Contact process

B
Manufacture of ammonia by Haber's process

C
Hydrolysis of sucrose in presence of dilute hydrochloric acid

D
Hydrogention of oil

Solution

Hydrolysis of sucrose in the presence of dilute hydrochloric acid is an example of homogenous catalysis. Here, the reactants, products, and catalysts are all in the same phase (aqueous phase).

$$ \displaystyle \text { sucrose (aq) } \xrightarrow { \text { dil HCl (aq) } } \text { glucose (aq) } + \text { fructose (aq)} $$

In heterogeneous catalysis, two or more phases are present. For example, in the hydrogenation of oil involves catalyst in the solid phase, hydrogen in gaseous state and oil in the liquid phase.
Question 4
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If liquid is dispersed in solid medium, then it is known as:

A
Sol

B
Emulsion

C
Liquid aerosol

D
Gel

Solution

Gels are the colloidal system in which liquid is dispersed phase and the dispersion medium is solid.

Examples are Cheese, butter, jellies etc.
Question 5
1 / -0

Incorrect statements is/ are from the following.

A
Adsorption is always exothermic in nature

B
$$CaCl_{2}$$ cause more coagulation of gold sol than $$AlCl_{3}$$

C
Surface tension of associated colloids increase with increase in concentration

D
With increase in concentration, molar conductance of strong electrolyte decreases repidly than associated colloids

Solution

A) Correct. Because $$\Delta H$$ of absorption is always negative. As it leads to a decrease in the residual forces on the surface of the absorbent.
B) Not correct. Higher positive charge will be more effective for coagulation.
Charge : $${ Al }^{ 3+ }>{ Ca }^{ 2+ }$$
C) Correct. Due to the existence of the attractive capillary force between the particles surface tension increases with increase in concentration.
D) Correct. As the molar conductivity decreases with increase in concentration for strong electrolytes.
Question 6
1 / -0

Out of the following, which reaction gives a colloidal solution?

A
$$Cu + HgCl_{2}\rightarrow CuCl_{2} + Hg$$

B
$$2HNO_{3} + 3H_{2}S\rightarrow 3S + 4H_{2}O + 2NO$$

C
$$2Mg + CO_{2} \rightarrow 2MgO + C$$

D
$$Cu + CuCl_{2}\xrightarrow {\text {excess HCl}} Cu_{2}Cl_{2}$$

Solution
Question 7
1 / -0

In which emulsion coloured droplets are obtained when oil soluble dye is added to it?

A
Cod liver oil

B
Cold cream

C
Hair cream

D
Milk

Solution

This is called dye test
When an oil soluble dye is added to emulsion only water in oil type emulsions show coloured droplets. Here only Milk is water in oil type emulsion because the fat phase or cream forms tiny droplets.
Option D is correct.
Question 8
1 / -0

Milk is:

A
gel

B
protein

C
emulsion

D
fat

Solution

Milk is an emulsion. Milk consists of particles of liquid dispersed in water.
Milk is an oil in water type emulsion.
Question 9
1 / -0

What type of colloidal system is fog?

A
Gas in liquid

B
Liquid in gas

C
Liquid in liquid

D
Solid in gas

Solution

In fog, liquid is the dispersed phase and gas in the dispersion medium.
So the correct answer is liquid in gas.
Question 10
1 / -0

There are many gas molecules $$NH_3$$, $$CO$$, $$CH_4$$ and $$SO_2$$ in a group once. They were discussing about who would be the better absorbed on charcoal. So they decided to have the race among themselves to prove it as to who would be absorbed more in the same time.
Who do you think won?

A
$$CO$$

B
$$NH_3$$

C
$$CH_4$$

D
$$SO_2$$

Solution

Because, A gas with a critical temperature i.e a more easily liquefiable gas adsorbed to a greater extent.
$$NH_3$$ is having higher critical temperature and large van der waals forces of attraction.

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Surface Chemistry Test - 36

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Surface Chemistry Test - 36

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Question 1

It is instantaneous

Monomolecular layer forms on the adsorbent

Less activation energy is required for it

Generally it results at low temperature and adsorption decreases with increase in temperature

Solution

Question 2

Adsorption is spontaneous

$$\Delta \, H$$ and $$\Delta \, S$$ are negative

It is reversible in nature

Degree of adsorption increases with temperature

Solution

Question 3

Manufacture of sulphuric acid by Contact process

Manufacture of ammonia by Haber's process

Hydrolysis of sucrose in presence of dilute hydrochloric acid

Hydrogention of oil

Solution

Question 4

Sol

Emulsion

Liquid aerosol

Gel

Solution

Question 5

Adsorption is always exothermic in nature

$$CaCl_{2}$$ cause more coagulation of gold sol than $$AlCl_{3}$$

Surface tension of associated colloids increase with increase in concentration

With increase in concentration, molar conductance of strong electrolyte decreases repidly than associated colloids

Solution

Question 6

$$Cu + HgCl_{2}\rightarrow CuCl_{2} + Hg$$

$$2HNO_{3} + 3H_{2}S\rightarrow 3S + 4H_{2}O + 2NO$$

$$2Mg + CO_{2} \rightarrow 2MgO + C$$

$$Cu + CuCl_{2}\xrightarrow {\text {excess HCl}} Cu_{2}Cl_{2}$$

Solution

Question 7

Cod liver oil

Cold cream

Hair cream

Milk

Solution

Question 8

gel

protein

emulsion

fat

Solution

Question 9

Gas in liquid

Liquid in gas

Liquid in liquid

Solid in gas

Solution

Question 10

$$CO$$

$$NH_3$$

$$CH_4$$

$$SO_2$$

Solution

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