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

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Q 1. Which one of the following statements is not correct?

The value of equilibrium constant is changed in the presence of a catalyst in the reaction at equilibrium.

B

Enzymes catalyse mainly biochemical reactions.

C

Coenzymes increase the catalytic activity of enzyme.

D

Catalyst does not initiate any reaction.

Explanation


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Q 2. The coagulation values in millimoles per litre of the electrolytes used for the coagulation of {tex} \mathrm { As } _ { 2 } \mathrm { S } _ { 3 } {/tex} are given below:
I. {tex} ( \mathrm { NaCl } ) = 52 , {/tex}
II.{tex} \left( \mathrm { BaCl } _ { 2 } \right) = 0.69, {/tex}
III.{tex}\left( \mathrm { MgSO } _ { 4 } \right) = 0.22 {/tex}{tex} \quad {/tex}
The correct order of their coagulating power is

A

{tex} \mathrm { I } > \mathrm { II } > \mathrm { III } {/tex}

B

{tex} \mathrm { II } > \mathrm { I } > \mathrm { III } {/tex}

{tex} \mathrm { III } > \mathrm { II } > \mathrm { I } {/tex}

D

{tex} \mathrm { III } > \mathrm { I } > \mathrm { II } {/tex}

Explanation


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Q 3. Fog is a colloidal solution of

A

solid in gas

B

gas in gas

liquid in gas

D

gas in liquid.

Explanation


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Q 4. Which one of the following characteristics is associated with adsorption?

A

{tex} \Delta G {/tex} and {tex} \Delta H {/tex} are negative but {tex} \Delta S {/tex} is positive.

B

{tex} \Delta G {/tex} and {tex} \Delta S {/tex} are negative but {tex} \Delta H {/tex} is positive.

C

{tex} \Delta G {/tex} is negative but {tex} \Delta H {/tex} and {tex} \Delta S {/tex} are positive.

{tex} \Delta G , \Delta H {/tex} and {tex} \Delta S {/tex} all are negative.

Explanation


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Q 5. The property of colloidal suspension used to determine the nature of charge on the particles is

A

dialysis

electrophoresis

C

sedimentation

D

ultrafiltration

Explanation

Sol particles move towards oppositely charged electrodes during the passage of current

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Q 6. Which property of colloids is not dependent on the charge on colloidal particles?

A

Coagulation

B

Electrophoresis

C

Electro-osmosis

Tyndall effect

Explanation

Tyndall effect is due to scattering of light by colloidal particles and not due to charge

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Q 7. In Freundlich adsorption isotherm, the value of 1{tex} / n {/tex} is

between 0 and 1 in all cases

B

between 2 and 4 in all cases

C

1 in case of physical absorption

D

1 in case of chemisorption.

Explanation


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Q 8. Which one of the following statements is incorrect about enzyme catalysis?

A

Enzymes are mostly proteinous in nature.

B

Enzyme action is specific.

C

Enzymes are denatured by ultraviolet rays and at high temperature.

Enzymes are least reactive at optimum temperature.

Explanation


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Q 9. The protecting power of lyophilic colloidal sol is expressed in terms of

A

coagulation value

gold number

C

critical micelle concentration

D

oxidation number

Explanation

Lyophobic sols are unstable, so they are stabilised by adding some lyophilic colloids which protect them from precipitation. Thus, lyophilic colloids are called protecting colloids. Their protecting power is expressed in terms of gold number. In other words, gold number can be defined as the minimum amount of lyophilic colloid in milligrams, which prevent the flocculation of 10 mL gold sol by the addition of 1 mL of 10% NaCl solution. NOTE Lesser the gold number, higher is the protecting power.

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Q 10. If {tex} x {/tex} is amount of adsorbate and {tex} m {/tex} is amount of adsorbent, which of the following relations is not related to adsorption process?

A

{tex} x / m = f ( p ) {/tex} at constant {tex} T {/tex}

B

{tex} x / m = f ( T ) {/tex} at constant {tex} p {/tex}

C

{tex} p = f ( T ) {/tex} at constant {tex} ( x / m ) {/tex}

{tex} \frac { x } { m } = p \times T {/tex}

Explanation

Freundlich adsorption isotherm can be expressed by the equation The Langmuir adsorption isotherm can be expressed by the equation Adsorption isotherms and adsorption Isobars are plotted only when either temperature or pressure is kept constant. It can not be plotted when none of the pressure or temperature is constant.

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Q 11. The Langmuir adsorption isotherm is deduced using the assumption

the adsorption sites are equivalent in their ability to adsorb the particles

B

the heat of adsorption varies with coverage

C

the adsorbed molecules interact with each other

D

the adsorption takes place in multilayers.

Explanation


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Q 12. A plot of {tex} \small \log (\frac {x}{m}) {/tex} versus {tex} \small \log p {/tex} for the adsorption of a gas on a solid gives a straight line with slope equal to

A

{tex} \log K {/tex}

B

{tex} - \log K {/tex}

C

{tex}n{/tex}

{tex} \frac {1} {n} {/tex}

Explanation


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Q 13. Which one of the following forms micelles in aqueous solution above certain concentration?

Dodecyl trimethyl ammonium chloride

B

Glucose

C

Urea

D

Pyridinium chloride

Explanation

Dodecyl trimethyl ammonium chloride will form micelles in aqueous solution above certain concentration. Here the cation has a polar ionic head and non-polar tail, required for micelle formation.

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Q 14. The enzyme which hydrolyses triglycerides to fatty acids and glycerol is called

A

maltase

lipase

C

zymase

D

pepsin

Explanation

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Q 15. According to the adsorption theory of catalysis, the speed of the reaction increases because

A

the concentration of reactant molecules at the active centres of the catalyst becomes high due to adsorption

B

in the process of adsorption, the activation energy of the molecules becomes large

C

adsorption produces heat which increases the speed of the reaction

adsorption lowers the activation energy of the reaction.

Explanation


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Q 16. Position of non polar and polar part in micelle

polar at outer surface but non polar at inner surface

B

polar at inner surface non polar at outer surface

C

distributed over all the surface

D

are present in the surface only.

Explanation


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Q 17. Which is not correct regarding the adsorption of a gas on surface of a solid?

On increasing temperature adsorption decreases continuously.

B

Enthalpy and entropy change is negative.

C

Adsorption is more for some specific substance.

D

It is a reversible reaction.

Explanation


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Q 18. Which one of the following method is commonly used method for destruction of colloid?

A

Dialysis

B

Condensation

C

Filteration by animal membrane

By adding electrolyte

Explanation


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Q 19. At the critical micelle concentration {tex} ( \mathrm { CMC } ) {/tex} the surfactant molecules

associate

B

dissociate

C

decompose

D

become completely soluble

Explanation


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Q 20. The ability of anion, to bring about coagulation of a given colloid, depends upon

A

magnitude of the charge

both magnitude and charge

C

its charge only

D

sign of the charge alone.

Explanation


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Q 21. A colloidal system has particles of which of the following size?

A

{tex} 10 ^ { - 9 } \mathrm { m } {/tex} to {tex} 10 ^ { - 12 } \mathrm { m } {/tex}

{tex} 10 ^ { - 6 } \mathrm { m } {/tex} to {tex} 10 ^ { - 9 } \mathrm { m } {/tex}

C

{tex} 10 ^ { - 4 } \mathrm { m } {/tex} to {tex} 10 ^ { - 10 } \mathrm { m } {/tex}

D

{tex} 10 ^ { - 5 } \mathrm { m } {/tex} to {tex} 10 ^ { - 7 } \mathrm { m } {/tex}

Explanation


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Q 22. When a few typical solutes are separated by a particular selective membrane such as protein particles, blood corpuscles, this process is called

A

transpiration

B

endosmosis

dialysis

D

diffusion

Explanation


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Q 23. In Langmuir's model of adsorption of a gas on a solid surface

the mass of gas striking a given area of surface is proportional to the pressure of the gas

B

the mass of gas striking a given area of surface is independent of the pressure of the gas

C

the rate of dissociation of adsorbed molecules from the surface does not depend on the surface covered

D

the adsorption at a single site on the surface may involve multiple molecules at the same time

Explanation