Surface Chemistry Sample Paper:- | Additional Study Material for Class 12 PDF Download

 Page 1


 
 
 
Surface Chemistry 
Multiple Choice Questions (Type-I) 
 
1.  Which of the following process does not occur at the interface of phases? 
(i) crystallisation 
(ii) heterogenous catalysis 
(iii) homogeneous catalysis 
(iv) corrosion 
Ans. (iii) 
 Explanation: In homogeneous catalysis, only, the reactant and product are in same phase 
and composition is uniform throughout. 
 
2.  At the equilibrium position in the process of adsorption ___________. 
(i) ?H > 0 
(ii) ?H = T?S 
(iii) ?H > T?S 
(iv) ?H < T?S 
Ans. (ii) 
 Explanation: At equilibrium ?G=0 
 ?G=?H-T?S 
  Therefore, ?H=T?S 
 
3.  Which of the following interface cannot be obtained? 
(i) liquid-liquid 
(ii) solid-liquid 
(iii) liquid-gas 
(iv) gas-gas 
Ans. (iv) 
 Explanation: Because gas-gas forms homogeneous composition. 
 
4. The term ‘sorption’ stands for ____________. 
(i) absorption 
(ii) adsorption 
(iii) both absorption and adsorption 
(iv) desorption 
Ans. (iii) 
Explanation: When adsorption and absorption occur simultaneously it is known as 
sorption. 
 
5.  Extent of physisorption of a gas increases with ___________. 
(i) increase in temperature. 
(ii) decrease in temperature. 
(iii) decrease in surface area of adsorbent. 
(iv) decrease in strength of van der Waals forces. 
Ans. (ii) 
Page 2


 
 
 
Surface Chemistry 
Multiple Choice Questions (Type-I) 
 
1.  Which of the following process does not occur at the interface of phases? 
(i) crystallisation 
(ii) heterogenous catalysis 
(iii) homogeneous catalysis 
(iv) corrosion 
Ans. (iii) 
 Explanation: In homogeneous catalysis, only, the reactant and product are in same phase 
and composition is uniform throughout. 
 
2.  At the equilibrium position in the process of adsorption ___________. 
(i) ?H > 0 
(ii) ?H = T?S 
(iii) ?H > T?S 
(iv) ?H < T?S 
Ans. (ii) 
 Explanation: At equilibrium ?G=0 
 ?G=?H-T?S 
  Therefore, ?H=T?S 
 
3.  Which of the following interface cannot be obtained? 
(i) liquid-liquid 
(ii) solid-liquid 
(iii) liquid-gas 
(iv) gas-gas 
Ans. (iv) 
 Explanation: Because gas-gas forms homogeneous composition. 
 
4. The term ‘sorption’ stands for ____________. 
(i) absorption 
(ii) adsorption 
(iii) both absorption and adsorption 
(iv) desorption 
Ans. (iii) 
Explanation: When adsorption and absorption occur simultaneously it is known as 
sorption. 
 
5.  Extent of physisorption of a gas increases with ___________. 
(i) increase in temperature. 
(ii) decrease in temperature. 
(iii) decrease in surface area of adsorbent. 
(iv) decrease in strength of van der Waals forces. 
Ans. (ii) 
 
 
 
Explanation: Since the adsorption (Solid+ Gas=Gas/Solid+ Heat) process is exothermic, 
the physical adsorption occurs readily at low temperature and decreases with increasing 
temperature as the equilibrium will shift in backward direction. (Le-Chatelier’s 
principle). 
 
6.  Extent of adsorption of adsorbate from solution phase increases with ________. 
(i) increase in amount of adsorbate in solution. 
(ii) decrease in surface area of adsorbent. 
(iii) increase in temperature of solution. 
(iv) decrease in amount of adsorbate in solution. 
Ans. (i) 
Explanation: The extent of adsorption depends on the concentration of the solute in 
solution as the concentration of adsorbate increase interaction between adsorbate and 
adsorbent increases thus the extent of adsorption increases. 
 
7.  Which one of the following is not applicable to the phenomenon of adsorption? 
(i) ?H > 0 
(ii) ?G < 0 
(iii) ?S < 0 
(iv) ?H < 0 
Ans. (i) 
 Explanation: Since adsorption is an exothermic process ?H cannot be greater than zero. 
 
8.  Which of the following is not a favourable condition for physical adsorption? 
(i) high pressure 
(ii) negative ?H 
(iii) higher critical temperature of adsorbate 
(iv) high temperature 
Ans. (iv) 
Explanation: High temperature is not favourable for physical adsorption since it is an 
exothermic process. 
 
9.  Physical adsorption of a gaseous species may change to chemical adsorption with 
______________. 
(i) decrease in temperature 
(ii) increase in temperature 
(iii) increase in surface area of adsorbent 
(iv) decrease in surface area of adsorbent 
Ans. (ii) 
Explanation: On increasing the temperature activation energy of the adsorbate molecule 
increases. Which can convert physical adsorption into chemisorptions. 
 
10.  In physisorption adsorbent does not show specificity for any particular gas 
because ______________. 
(i) involved van der Waals forces are universal. 
Page 3


 
 
 
Surface Chemistry 
Multiple Choice Questions (Type-I) 
 
1.  Which of the following process does not occur at the interface of phases? 
(i) crystallisation 
(ii) heterogenous catalysis 
(iii) homogeneous catalysis 
(iv) corrosion 
Ans. (iii) 
 Explanation: In homogeneous catalysis, only, the reactant and product are in same phase 
and composition is uniform throughout. 
 
2.  At the equilibrium position in the process of adsorption ___________. 
(i) ?H > 0 
(ii) ?H = T?S 
(iii) ?H > T?S 
(iv) ?H < T?S 
Ans. (ii) 
 Explanation: At equilibrium ?G=0 
 ?G=?H-T?S 
  Therefore, ?H=T?S 
 
3.  Which of the following interface cannot be obtained? 
(i) liquid-liquid 
(ii) solid-liquid 
(iii) liquid-gas 
(iv) gas-gas 
Ans. (iv) 
 Explanation: Because gas-gas forms homogeneous composition. 
 
4. The term ‘sorption’ stands for ____________. 
(i) absorption 
(ii) adsorption 
(iii) both absorption and adsorption 
(iv) desorption 
Ans. (iii) 
Explanation: When adsorption and absorption occur simultaneously it is known as 
sorption. 
 
5.  Extent of physisorption of a gas increases with ___________. 
(i) increase in temperature. 
(ii) decrease in temperature. 
(iii) decrease in surface area of adsorbent. 
(iv) decrease in strength of van der Waals forces. 
Ans. (ii) 
 
 
 
Explanation: Since the adsorption (Solid+ Gas=Gas/Solid+ Heat) process is exothermic, 
the physical adsorption occurs readily at low temperature and decreases with increasing 
temperature as the equilibrium will shift in backward direction. (Le-Chatelier’s 
principle). 
 
6.  Extent of adsorption of adsorbate from solution phase increases with ________. 
(i) increase in amount of adsorbate in solution. 
(ii) decrease in surface area of adsorbent. 
(iii) increase in temperature of solution. 
(iv) decrease in amount of adsorbate in solution. 
Ans. (i) 
Explanation: The extent of adsorption depends on the concentration of the solute in 
solution as the concentration of adsorbate increase interaction between adsorbate and 
adsorbent increases thus the extent of adsorption increases. 
 
7.  Which one of the following is not applicable to the phenomenon of adsorption? 
(i) ?H > 0 
(ii) ?G < 0 
(iii) ?S < 0 
(iv) ?H < 0 
Ans. (i) 
 Explanation: Since adsorption is an exothermic process ?H cannot be greater than zero. 
 
8.  Which of the following is not a favourable condition for physical adsorption? 
(i) high pressure 
(ii) negative ?H 
(iii) higher critical temperature of adsorbate 
(iv) high temperature 
Ans. (iv) 
Explanation: High temperature is not favourable for physical adsorption since it is an 
exothermic process. 
 
9.  Physical adsorption of a gaseous species may change to chemical adsorption with 
______________. 
(i) decrease in temperature 
(ii) increase in temperature 
(iii) increase in surface area of adsorbent 
(iv) decrease in surface area of adsorbent 
Ans. (ii) 
Explanation: On increasing the temperature activation energy of the adsorbate molecule 
increases. Which can convert physical adsorption into chemisorptions. 
 
10.  In physisorption adsorbent does not show specificity for any particular gas 
because ______________. 
(i) involved van der Waals forces are universal. 
 
 
 
(ii) gases involved behave like ideal gases. 
(iii) enthalpy of adsorption is low. 
(iv) it is a reversible process. 
Ans. (i) 
  
11.  Which of the following is an example of absorption? 
(i) Water on silica gel 
(ii) Water on calcium chloride 
(iii) Hydrogen on finely divided nickel 
(iv) Oxygen on metal surface 
Ans. (ii) 
 
12.  On the basis of data given below predict which of the following gases shows least 
adsorption on a definite amount of charcoal? 
Gas CO2 SO2 CH4 H2 
Critical temp./K 304 630 190 33 
(i) CO2 
(ii) SO2 
(iii) CH4 
(iv) H2 
Ans. (iv) 
Explanation: Lesser the value of critical temp of gases lesser will the force of attraction 
among molecules and least will be the adsorption. 
 
13.  In which of the following reactions heterogenous catalysis is involved? 
(a) 
( )
2 2 3
2 ( ) ( ) 2 ( )
NO g
SO g O g SO g + --- ? 
(b) 
( )
2 3
2 ( ) 2 ( )
Pt s
SO g SO g ?-- - 
(c) 
( )
2 2 3
( ) 3 ( ) 2 ( )
Fe s
N g H g NH g + --- ? 
(d) 
3 3 2 3 3
( ) ( ) ( ) ( )
HCl
CH COOCH l H O l CH COOH aq CH OH aq + -- - ? + 
(i) (b), (c) 
(ii) (b), (c), (d) 
(iii) (a), (b), (c) 
(iv) (d) 
Ans. (i) (b), (c) 
Explanation: When the reactant and catalyst are in different phase it is known as 
heterogeneous catalysis. 
 
14.  At high concentration of soap in water, soap behaves as ____________. 
(i) molecular colloid 
(ii) associated colloid 
(iii) macromolecular colloid 
(iv) lyophilic colloid 
Ans. (ii) 
Page 4


 
 
 
Surface Chemistry 
Multiple Choice Questions (Type-I) 
 
1.  Which of the following process does not occur at the interface of phases? 
(i) crystallisation 
(ii) heterogenous catalysis 
(iii) homogeneous catalysis 
(iv) corrosion 
Ans. (iii) 
 Explanation: In homogeneous catalysis, only, the reactant and product are in same phase 
and composition is uniform throughout. 
 
2.  At the equilibrium position in the process of adsorption ___________. 
(i) ?H > 0 
(ii) ?H = T?S 
(iii) ?H > T?S 
(iv) ?H < T?S 
Ans. (ii) 
 Explanation: At equilibrium ?G=0 
 ?G=?H-T?S 
  Therefore, ?H=T?S 
 
3.  Which of the following interface cannot be obtained? 
(i) liquid-liquid 
(ii) solid-liquid 
(iii) liquid-gas 
(iv) gas-gas 
Ans. (iv) 
 Explanation: Because gas-gas forms homogeneous composition. 
 
4. The term ‘sorption’ stands for ____________. 
(i) absorption 
(ii) adsorption 
(iii) both absorption and adsorption 
(iv) desorption 
Ans. (iii) 
Explanation: When adsorption and absorption occur simultaneously it is known as 
sorption. 
 
5.  Extent of physisorption of a gas increases with ___________. 
(i) increase in temperature. 
(ii) decrease in temperature. 
(iii) decrease in surface area of adsorbent. 
(iv) decrease in strength of van der Waals forces. 
Ans. (ii) 
 
 
 
Explanation: Since the adsorption (Solid+ Gas=Gas/Solid+ Heat) process is exothermic, 
the physical adsorption occurs readily at low temperature and decreases with increasing 
temperature as the equilibrium will shift in backward direction. (Le-Chatelier’s 
principle). 
 
6.  Extent of adsorption of adsorbate from solution phase increases with ________. 
(i) increase in amount of adsorbate in solution. 
(ii) decrease in surface area of adsorbent. 
(iii) increase in temperature of solution. 
(iv) decrease in amount of adsorbate in solution. 
Ans. (i) 
Explanation: The extent of adsorption depends on the concentration of the solute in 
solution as the concentration of adsorbate increase interaction between adsorbate and 
adsorbent increases thus the extent of adsorption increases. 
 
7.  Which one of the following is not applicable to the phenomenon of adsorption? 
(i) ?H > 0 
(ii) ?G < 0 
(iii) ?S < 0 
(iv) ?H < 0 
Ans. (i) 
 Explanation: Since adsorption is an exothermic process ?H cannot be greater than zero. 
 
8.  Which of the following is not a favourable condition for physical adsorption? 
(i) high pressure 
(ii) negative ?H 
(iii) higher critical temperature of adsorbate 
(iv) high temperature 
Ans. (iv) 
Explanation: High temperature is not favourable for physical adsorption since it is an 
exothermic process. 
 
9.  Physical adsorption of a gaseous species may change to chemical adsorption with 
______________. 
(i) decrease in temperature 
(ii) increase in temperature 
(iii) increase in surface area of adsorbent 
(iv) decrease in surface area of adsorbent 
Ans. (ii) 
Explanation: On increasing the temperature activation energy of the adsorbate molecule 
increases. Which can convert physical adsorption into chemisorptions. 
 
10.  In physisorption adsorbent does not show specificity for any particular gas 
because ______________. 
(i) involved van der Waals forces are universal. 
 
 
 
(ii) gases involved behave like ideal gases. 
(iii) enthalpy of adsorption is low. 
(iv) it is a reversible process. 
Ans. (i) 
  
11.  Which of the following is an example of absorption? 
(i) Water on silica gel 
(ii) Water on calcium chloride 
(iii) Hydrogen on finely divided nickel 
(iv) Oxygen on metal surface 
Ans. (ii) 
 
12.  On the basis of data given below predict which of the following gases shows least 
adsorption on a definite amount of charcoal? 
Gas CO2 SO2 CH4 H2 
Critical temp./K 304 630 190 33 
(i) CO2 
(ii) SO2 
(iii) CH4 
(iv) H2 
Ans. (iv) 
Explanation: Lesser the value of critical temp of gases lesser will the force of attraction 
among molecules and least will be the adsorption. 
 
13.  In which of the following reactions heterogenous catalysis is involved? 
(a) 
( )
2 2 3
2 ( ) ( ) 2 ( )
NO g
SO g O g SO g + --- ? 
(b) 
( )
2 3
2 ( ) 2 ( )
Pt s
SO g SO g ?-- - 
(c) 
( )
2 2 3
( ) 3 ( ) 2 ( )
Fe s
N g H g NH g + --- ? 
(d) 
3 3 2 3 3
( ) ( ) ( ) ( )
HCl
CH COOCH l H O l CH COOH aq CH OH aq + -- - ? + 
(i) (b), (c) 
(ii) (b), (c), (d) 
(iii) (a), (b), (c) 
(iv) (d) 
Ans. (i) (b), (c) 
Explanation: When the reactant and catalyst are in different phase it is known as 
heterogeneous catalysis. 
 
14.  At high concentration of soap in water, soap behaves as ____________. 
(i) molecular colloid 
(ii) associated colloid 
(iii) macromolecular colloid 
(iv) lyophilic colloid 
Ans. (ii) 
 
 
 
Explanation: There are some substances which at low concentrations behave as normal 
strong electrolytes, but at higher concentrations exhibit colloidal behavior due to the 
formation of aggregates. The aggregated particles thus formed are called micelles. These 
are also known as associated colloids. 
 
15.  Which of the following will show Tyndall effect? 
(i) Aqueous solution of soap below critical micelle concentration. 
(ii) Aqueous solution of soap above critical micelle concentration. 
(iii) Aqueous solution of sodium chloride. 
(iv) Aqueous solution of sugar. 
Ans. (ii) 
Explanation: Tyndall effect is the optical property shown by the colloidal particle. Above 
critical micelle concentration, a solution of soap behave as associated colloid that is why 
it shows tyndall effect. 
 
16.  Method by which lyophobic sol can be protected. 
(i) By addition of oppositely charged sol. 
(ii) By addition of an electrolyte. 
(iii) By addition of lyophilic sol. 
(iv) By boiling. 
Ans. (iii) 
Explanation: Lyophilic colloids have a unique property of protecting lyophobic colloids. 
When a lyophilic sol is added to the lyophobic sol, the lyophilic particles form a layer 
around lyophobic particles and thus protect the latter from electrolytes. Lyophilic 
colloids used for this purpose are called protective colloids. 
 
17.  Freshly prepared precipitate sometimes gets converted to colloidal solution by 
___________. 
(i) coagulation 
(ii) electrolysis 
(iii) diffusion 
(iv) peptisation 
Ans. (iv) 
Explanation: Peptisation is the process in which freshly prepared precipitate can be 
converted into colloidal solution. 
 
18.  Which of the following electrolytes will have maximum coagulating 
valueforAgI/Ag
+
sol? 
(i) Na2S 
(ii) Na3PO4 
(iii) Na2SO4 
(iv) NaCl 
Ans. (ii) 
Explanation: Higher the value of oppositely charge electrolyte faster will be the rate of 
coagulation. 
Page 5


 
 
 
Surface Chemistry 
Multiple Choice Questions (Type-I) 
 
1.  Which of the following process does not occur at the interface of phases? 
(i) crystallisation 
(ii) heterogenous catalysis 
(iii) homogeneous catalysis 
(iv) corrosion 
Ans. (iii) 
 Explanation: In homogeneous catalysis, only, the reactant and product are in same phase 
and composition is uniform throughout. 
 
2.  At the equilibrium position in the process of adsorption ___________. 
(i) ?H > 0 
(ii) ?H = T?S 
(iii) ?H > T?S 
(iv) ?H < T?S 
Ans. (ii) 
 Explanation: At equilibrium ?G=0 
 ?G=?H-T?S 
  Therefore, ?H=T?S 
 
3.  Which of the following interface cannot be obtained? 
(i) liquid-liquid 
(ii) solid-liquid 
(iii) liquid-gas 
(iv) gas-gas 
Ans. (iv) 
 Explanation: Because gas-gas forms homogeneous composition. 
 
4. The term ‘sorption’ stands for ____________. 
(i) absorption 
(ii) adsorption 
(iii) both absorption and adsorption 
(iv) desorption 
Ans. (iii) 
Explanation: When adsorption and absorption occur simultaneously it is known as 
sorption. 
 
5.  Extent of physisorption of a gas increases with ___________. 
(i) increase in temperature. 
(ii) decrease in temperature. 
(iii) decrease in surface area of adsorbent. 
(iv) decrease in strength of van der Waals forces. 
Ans. (ii) 
 
 
 
Explanation: Since the adsorption (Solid+ Gas=Gas/Solid+ Heat) process is exothermic, 
the physical adsorption occurs readily at low temperature and decreases with increasing 
temperature as the equilibrium will shift in backward direction. (Le-Chatelier’s 
principle). 
 
6.  Extent of adsorption of adsorbate from solution phase increases with ________. 
(i) increase in amount of adsorbate in solution. 
(ii) decrease in surface area of adsorbent. 
(iii) increase in temperature of solution. 
(iv) decrease in amount of adsorbate in solution. 
Ans. (i) 
Explanation: The extent of adsorption depends on the concentration of the solute in 
solution as the concentration of adsorbate increase interaction between adsorbate and 
adsorbent increases thus the extent of adsorption increases. 
 
7.  Which one of the following is not applicable to the phenomenon of adsorption? 
(i) ?H > 0 
(ii) ?G < 0 
(iii) ?S < 0 
(iv) ?H < 0 
Ans. (i) 
 Explanation: Since adsorption is an exothermic process ?H cannot be greater than zero. 
 
8.  Which of the following is not a favourable condition for physical adsorption? 
(i) high pressure 
(ii) negative ?H 
(iii) higher critical temperature of adsorbate 
(iv) high temperature 
Ans. (iv) 
Explanation: High temperature is not favourable for physical adsorption since it is an 
exothermic process. 
 
9.  Physical adsorption of a gaseous species may change to chemical adsorption with 
______________. 
(i) decrease in temperature 
(ii) increase in temperature 
(iii) increase in surface area of adsorbent 
(iv) decrease in surface area of adsorbent 
Ans. (ii) 
Explanation: On increasing the temperature activation energy of the adsorbate molecule 
increases. Which can convert physical adsorption into chemisorptions. 
 
10.  In physisorption adsorbent does not show specificity for any particular gas 
because ______________. 
(i) involved van der Waals forces are universal. 
 
 
 
(ii) gases involved behave like ideal gases. 
(iii) enthalpy of adsorption is low. 
(iv) it is a reversible process. 
Ans. (i) 
  
11.  Which of the following is an example of absorption? 
(i) Water on silica gel 
(ii) Water on calcium chloride 
(iii) Hydrogen on finely divided nickel 
(iv) Oxygen on metal surface 
Ans. (ii) 
 
12.  On the basis of data given below predict which of the following gases shows least 
adsorption on a definite amount of charcoal? 
Gas CO2 SO2 CH4 H2 
Critical temp./K 304 630 190 33 
(i) CO2 
(ii) SO2 
(iii) CH4 
(iv) H2 
Ans. (iv) 
Explanation: Lesser the value of critical temp of gases lesser will the force of attraction 
among molecules and least will be the adsorption. 
 
13.  In which of the following reactions heterogenous catalysis is involved? 
(a) 
( )
2 2 3
2 ( ) ( ) 2 ( )
NO g
SO g O g SO g + --- ? 
(b) 
( )
2 3
2 ( ) 2 ( )
Pt s
SO g SO g ?-- - 
(c) 
( )
2 2 3
( ) 3 ( ) 2 ( )
Fe s
N g H g NH g + --- ? 
(d) 
3 3 2 3 3
( ) ( ) ( ) ( )
HCl
CH COOCH l H O l CH COOH aq CH OH aq + -- - ? + 
(i) (b), (c) 
(ii) (b), (c), (d) 
(iii) (a), (b), (c) 
(iv) (d) 
Ans. (i) (b), (c) 
Explanation: When the reactant and catalyst are in different phase it is known as 
heterogeneous catalysis. 
 
14.  At high concentration of soap in water, soap behaves as ____________. 
(i) molecular colloid 
(ii) associated colloid 
(iii) macromolecular colloid 
(iv) lyophilic colloid 
Ans. (ii) 
 
 
 
Explanation: There are some substances which at low concentrations behave as normal 
strong electrolytes, but at higher concentrations exhibit colloidal behavior due to the 
formation of aggregates. The aggregated particles thus formed are called micelles. These 
are also known as associated colloids. 
 
15.  Which of the following will show Tyndall effect? 
(i) Aqueous solution of soap below critical micelle concentration. 
(ii) Aqueous solution of soap above critical micelle concentration. 
(iii) Aqueous solution of sodium chloride. 
(iv) Aqueous solution of sugar. 
Ans. (ii) 
Explanation: Tyndall effect is the optical property shown by the colloidal particle. Above 
critical micelle concentration, a solution of soap behave as associated colloid that is why 
it shows tyndall effect. 
 
16.  Method by which lyophobic sol can be protected. 
(i) By addition of oppositely charged sol. 
(ii) By addition of an electrolyte. 
(iii) By addition of lyophilic sol. 
(iv) By boiling. 
Ans. (iii) 
Explanation: Lyophilic colloids have a unique property of protecting lyophobic colloids. 
When a lyophilic sol is added to the lyophobic sol, the lyophilic particles form a layer 
around lyophobic particles and thus protect the latter from electrolytes. Lyophilic 
colloids used for this purpose are called protective colloids. 
 
17.  Freshly prepared precipitate sometimes gets converted to colloidal solution by 
___________. 
(i) coagulation 
(ii) electrolysis 
(iii) diffusion 
(iv) peptisation 
Ans. (iv) 
Explanation: Peptisation is the process in which freshly prepared precipitate can be 
converted into colloidal solution. 
 
18.  Which of the following electrolytes will have maximum coagulating 
valueforAgI/Ag
+
sol? 
(i) Na2S 
(ii) Na3PO4 
(iii) Na2SO4 
(iv) NaCl 
Ans. (ii) 
Explanation: Higher the value of oppositely charge electrolyte faster will be the rate of 
coagulation. 
 
 
 
 
19.  A colloidal system having a solid substance as a dispersed phase and a liquid as a 
dispersion medium is classified as ____________. 
(i) solid sol 
(ii) gel 
(iii) emulsion 
(iv) sol 
Ans. (iv) 
Explanation: Solid + liquid= sol (here solid is the dispersed phase and liquid is the 
dispersion medium.) 
 
20.  The values of colligative properties of colloidal solution are of small order in 
comparison to those shown by true solutions of same concentration because of 
colloidal particles __________________. 
(i) exhibit enormous surface area. 
(ii) remain suspended in the dispersion medium. 
(iii) form lyophilic colloids. 
(iv) are comparatively less in number. 
Ans. (iv) 
Explanation: Colloidal particles being bigger aggregates, the number of particles in a 
colloidal solution is comparatively small as compared to a true solution. Hence, the values 
of colligative properties (osmotic pressure, lowering in vapour pressure, depression in 
freezing point and elevation in boiling point) are of small order as compared to values 
shown by true solutions at same concentration. 
 
21.  Arrange the following diagrams in correct sequence of steps involved in the 
mechanism of catalysis, in accordance with modern adsorption theory.