Surface Chemistry

Which one is an example of heterogeneous catalysis?

1. Hydrolysis of sugar catalysed by H+ ions.
2. Decomposition of ozone in presence of nitrogen monoxide.
3. Combination between dinitrogen and dihydrogen to form ammonia in the presence of finely divided iron.
4. Oxidation of sulphur dioxide into sulphur trioxide in the presence of oxides of nitrogen.

Pumice stone is an example of -

1. gel
2. solid sol
3. foam
4. sol

Given below are two statements In the light of the above statements, choose the most appropriate answer from the options given below

1. Both Statement I and Statement II are correct.
2. Both Statement I and Statement II are incorrect.
3. Statement I is correct but Statement II is incorrect.
4. Statement I is incorrect but Statement II is correct.

Shown below are adsorption isotherms for a gas 'X' at temperatures T1, T2 and T3 : [figure] p and xm represent pressure and extent of adsorption, respectively. The correct order of temperatures for the given adsorption is :

1. T1 = T2 > T3
2. T1 > T2 > T3
3. T3 > T2 > T1
4. T1 = T2 = T3

The right option for the statement "Tyndall effect is exhibited by", is :

1. Urea solution
2. NaCl solution
3. Glucose solution
4. Starch solution

Measuring Zeta potential is useful in determining which property of colloidal solution?

1. Solubility
2. Stability of the colloidal particles
3. Size of the colloidal particles
4. Viscosity

On which of the following properties does the coagulating power of an ion depend?

1. The magnitude of the charge on the ion alone
2. Size of the ion alone
3. Both magnitude and sign of the charge on the ion
4. The sign of charge on the ion alone

Which one of the following statements is not correct?

1. The value of equilibrium constant is changed in the presence of a catalyst in the reaction at equilibrium.
2. Enzymes catalyse mainly bio-chemical reactions.
3. Coenzymes increase the catalytic activity of enzyme.
4. Catalyst does not initiate any reaction.

Fog is a colloidal solution of

1. solid in gas
2. gas in gas
3. liquid in gas
4. gas in liquid.

Which one of the following characteristics is associated with adsorption?

1. G and H are negative but S is positive.
2. G and S are negative but H is positive.
3. G is negative but H and S are positive.
4. G, H and S all are negative.

The coagulation values in millimoles per litre of the electrolytes used for the coagulation of As2S3 are given below : I. (NaCl) = 52, II. (BaCl2) = 0.69, III. (MgSO4) = 0.22 The correct order of their coagulating power is

1. I > II > III
2. II > I > III
3. III > II > I
4. III > I > II

Which property of colloidal solution is independent of charge on the colloidal particles?

1. Electro-osmosis
2. Tyndall effect
3. Coagulation
4. Electrophoresis

Which of the following statements is correct for the spontaneous adsorption of a gas?

1. is negative and, therefore, should be highly positive.
2. is negative and, therefore, should be highly negative.
3. is positive and, therefore, should be negative.
4. is positive and, therefore, should also be highly positive.

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

1. Coagulation
2. Electrophoresis
3. Electro-osmosis
4. Tyndall effect

In Freundlich adsorption isotherm, the value of 1n is

1. between 0 and 1 in all cases
2. between 2 and 4 in all cases
3. 1 in case of physical adsorption
4. 1 in case of chemisorption.

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

1. Enzymes are mostly proteinous in nature.
2. Enzyme action is specific.
3. Enzymes are denatured by ultraviolet rays and at high temperature.
4. Enzymes are least reactive at optimum temperature.

The protecting power of lyophilic colloidal sol is expressed in terms of

1. coagulation value
2. gold number
3. critical micelle concentration
4. oxidation number

If x is amount of adsorbate and m is amount of adsorbent, which of the following relations is not related to adsorption process?

1. x/m = f(p) at constant T
2. x/m = f(T) at constant p
3. p = f(T) at constant (x/m)
4. xm = p T

The Langmuir adsorption isotherm is deduced using the assumption

1. the adsorption sites are equivalent in their ability to adsorb the particles
2. the heat of adsorption varies with coverage
3. the adsorbed molecules interact with each other
4. the adsorption takes place in multilayers

A plot of (x/m) versus p for the adsorption of a gas on a solid gives a straight line with slope equal to

1. K
2. - K
3. n
4. 1/n

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

1. Dodecyl trimethyl ammonium chloride
2. Glucose
3. Urea
4. Pyridinium chloride

Which of the following forms cationic micelles above certain concentration?

1. Sodium dodecyl sulphate
2. Sodium acetate
3. Urea
4. Cetyltrimethylammonium bromide.

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

1. the concentration of reactant molecules at the active centres of the catalyst becomes high due to adsorption
2. in the process of adsorption, the activation energy of the molecules becomes large
3. adsorption produces heat which increases the speed of the reaction
4. adsorption lowers the activation energy of the reaction.

Position of non-polar and polar part in micelle

1. polar at outer surface but non-polar at inner surface
2. polar at inner surface but non-polar at outer surface
3. distributed over all the surface
4. are present in the surface only

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

1. On increasing temperature adsorption increases continuously.
2. Enthalpy and entropy change is negative.
3. Adsorption is more for some specific substance.
4. It is a reversible reaction.

Which one of the following methods is commonly used for the destruction of a colloid?

1. Dialysis
2. Condensation
3. Filtration by animal membrane
4. By adding electrolyte