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JEE Advanced

Explore popular questions from Surface Chemistry for JEE Advanced. This collection covers Surface Chemistry previous year JEE Advanced questions hand picked by experienced teachers.

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Q 1. Adsorption of gases on solids is accompanied with

A

increase in enthalpy

B

increase in entropy

decrease in entropy

D

increase in free energy

Explanation

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Q 2. Which of the following statements is correct for lyophilic sols?

A

The coagulation of the sols is irreversible in nature

B

They are formed by inorganic substances

They are self stabilised

D

They are readily coagulated by addition of electrolytes.

Explanation

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Q 3. Among the following, the surfactant that will form micelles in aqueous solution at the lowest molar concentration at ambient conditions is

{tex} \mathrm { CH } _ { 3 } \left( \mathrm { CH } _ { 2 } \right) _ { 15 } \mathrm { N } ^ { + } \left( \mathrm { CH } _ { 3 } \right) _ { 3 } \mathrm { Br } ^ { - } {/tex}

B

{tex} \mathrm { CH } _ { 3 } \left( \mathrm { CH } _ { 2 } \right) _ { 11 } \mathrm { OSO } _ { 3 }^- \mathrm { Na } ^ { + } {/tex}

C

{tex} \mathrm { CH } _ { 3 } \left( \mathrm { CH } _ { 2 } \right) _ { 6 } \mathrm { COO }^- \mathrm { Na } ^ { + } {/tex}

D

{tex} \mathrm { CH } _ { 3 } \left( \mathrm { CH } _ { 2 } \right) _ { 11 } \mathrm { N } ^ { + } \left( \mathrm { CH } _ { 3 } \right) _ { 3 } \mathrm { Br } ^ { - } {/tex}

Explanation

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Q 4. Among the electrolytes {tex} \mathrm { Na } _ { 2 } \mathrm { SO } _ { 4 } , \mathrm { CaCl } _ { 2 } , \mathrm { Al } _ { 2 } \left( \mathrm { SO } _ { 4 } \right) _ { 3 } {/tex} and {tex} \mathrm { NH } _ { 4 } \mathrm { Cl } {/tex}, the most effective coagulating agent for {tex} \mathrm { Sb } _ { 2 } \mathrm { S } _ { 3 } {/tex} sol is

A

{tex} \mathrm { Na } _ { 2 } \mathrm { SO } _ { 4 } {/tex}

B

{tex} \mathrm { CaCl } _ { 2 } {/tex}

{tex} \mathrm { Al } _ { 2 } \left( \mathrm { SO } _ { 4 } \right) _ { 3 } {/tex}

D

{tex} \mathrm { NH } _ { 4 } \mathrm { Cl } {/tex}

Explanation

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Q 5. Methylene blue, from its aqueous solution, is adsorbed on activated charcoal at {tex} 25 ^ { \circ } \mathrm { C } . {/tex} For this process, the correct statement is

A

The adsorption requires activation at {tex} 25 ^ { \circ } \mathrm { C } {/tex}

The adsorption is accompanied by a decrease in enthalpy

C

The adsorption increases with increase of temperature

D

The adsorption is irreversible.

Explanation

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Q 6.

Aluminium hydroxide forms a positively charged sol. Which of the following ionic substance should be most effective in coagulating the sol?

A

B

C

Explanation

is positively charged sol. has greater negative charge. Hence, it is most effective in coagulation of sol

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Q 7.

The colloidal sol of prefers to adsorb

A

B

D

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Q 8.

Which of the following is present at the time of cracking of hydrocarbons?

A

Copper

Zeolite

C

Nickel

D

Molybdenum

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Q 9.

The stabilization of a dispersed phase in a lyophobic colloid is due to

A

The adsorption of charged substances on dispersed phase

B

The large electro-kinetic potential developed in the colloid

The formation of an electrical layer between two phases

D

The viscosity of the medium

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Q 10.

Which of the following can act as a protective colloid?

Gelatin

B

Silica gel

C

Oil-in-water emulsion

D

All correct

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Q 11.

Which one of the following is a natural colloid?

A

Sodium chloride solution

B

Cane sugar solution

C

Urea solution

Blood

Explanation

Blood is a natural colloid

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Q 12.

Gold number of a lyophilic sol is such a property that

A

The larger its value, the greater is the peptizing power

B

The lower its value, the greater is the peptizing power

The lower its value, the greater is the protecting power

D

The larger its value, the greater is the protecting power

Explanation

The reciprocal of gold number is directly proportional to the protecting power

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Q 13.

The diameter of colloidal particle is of the order

A

B

C

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Q 14.

Compared to common colloidal sols micelles have:

A

Higher colligative properties

Lower colligative properties

C

Same colligative properties

D

None is true

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Q 15.

The colligative property of a colloidal sol compared to the solution of non-electrolyte of same concentration will be

A

Same

B

Higher

Lower

D

Higher or lower

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Q 16.

Among the electrolytes the most effective coagulation agent for sol is

A

B

D

Explanation

is an anionic sol, therefore cation of highest valency ( in the present case) would be most effective coagulating agent.

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Q 17.

Catalyst used in polymerization of ethene is:

A

and

Fe, Co

C

D

Zeolites

Explanation

For polymerization of ethene, Fe and Co is used

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Q 18.

The process of removing dissolved impurities from a colloidal system by means of diffusion through suitable membrane under the influence of an electric field is called

A

Electro-osmosis

Electrodialysis

C

Electrophoresis

D

Peptization

Explanation

Dialysis is a process of purifying a substance

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Q 19.

Softening of hard water is done using sodium aluminium silicate (zeolite). This causes

Adsorption of and ions of hard water replacing ions

B

Adsorption of and ions of hard water replacing ions

C

Both true

D

None is true

Explanation

Hardness of water is due to carbonate or sulphate of and ions. When sodium aluminium silicate is added replaces and by adsorption, and hence water become soft

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Q 20.

Lyophilic sols are

A

Irreversible sols

B

They are prepared from inorganic compounds

C

Coagulated by adding electrolytes

Self-stabilising

Explanation

Lyophilic sols are self stabilizing because these sols are reversible and are highly hydrated in the solution.

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Q 21.

Soaking of water by a sponge is an example of

A

Simple adsorption

B

Physical adsorption

C

Chemisorption

Absorption

Explanation

Soaking of water by a sponge is adsorption because water also accumulates in bulk of sponge as well as on the surface of it

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Q 22.

Among the following, the surfactant that will form micelles in aqueous solution at the lowest molar concentration at ambient conditions, is

B

C

D

Explanation

Sodium dodecyl sulphate (SDS)

CMC (mm)>-10

Hexadecyl trimethyl ammonium bromide (CTAB)

Note At a certain concentration surfactant molecules start to aggregate and form micelle, the concentration is called critical micellisationconcentration(CMC).

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Q 23.

Which is not the correct statement for a catalyst?

It does not alter

B

The surface of a catalyst adsorbs reactants

C

Catalyst may form intermediates with reactants

D

Action of enzyme catalyst is always specific

Explanation

Catalyst changes the activation energy

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Q 24.

Which one of the following statements is wrong about adsorption?

A

It is a selective and specific process

B

It is a reversible process

C

An increase in the gaseous adsorbate causes an increase in a adsorption. However, at high pressure, the adsorption becomes constant

It is an endothermic process

Explanation

Adsorption is an exothermic process

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Q 25.

Micelles are

A

Ideal solution

Associated colloids

C

Adsorbed surfaces

D

Absorbent solutes