Surface Chemistry Practice Questions - DPP for JEE

 Page 1


1. (a) Smaller the charge on anion, lesser will be its coagulating power.
?  KBr have Br
–
 with least charge of – 1 on Br thus KBr is least
effective in coagulating Fe(OH)
3
.
2. (b)
3. (b) According to Freundlich equation.
4. (b) 1 micron µ = 10
–6
 m and 1 millimicron = 10
–7
 m.
5. (d) All are irreversible colloidal systems.
6. (d) Cetyl trimethyl ammonium bromide,
 is a cationic micelle
7. (a)
8. (c) It is due to impact of molecules of dispersion medium on the
colloidal particles.
9. (c)
10. (c) The movement towards anode shows that sol is negative. For
coagulation of negative sol. Cation with higher charge is more
effective.
11. (d)  Fe(OH)
3
 is positive sol. K
3
[Fe(CN)
6
] will provide [Fe(CN)
6
]
3–
 for
coagulation.
12. (d) Tannin used in leather industry contains negatively charged
colloidal particles.
13. (c) Alum coagulates mud particles and helps in purifying water.
14. (a) On increasing temperature adsorption of a gas on surface of solid
Page 2


1. (a) Smaller the charge on anion, lesser will be its coagulating power.
?  KBr have Br
–
 with least charge of – 1 on Br thus KBr is least
effective in coagulating Fe(OH)
3
.
2. (b)
3. (b) According to Freundlich equation.
4. (b) 1 micron µ = 10
–6
 m and 1 millimicron = 10
–7
 m.
5. (d) All are irreversible colloidal systems.
6. (d) Cetyl trimethyl ammonium bromide,
 is a cationic micelle
7. (a)
8. (c) It is due to impact of molecules of dispersion medium on the
colloidal particles.
9. (c)
10. (c) The movement towards anode shows that sol is negative. For
coagulation of negative sol. Cation with higher charge is more
effective.
11. (d)  Fe(OH)
3
 is positive sol. K
3
[Fe(CN)
6
] will provide [Fe(CN)
6
]
3–
 for
coagulation.
12. (d) Tannin used in leather industry contains negatively charged
colloidal particles.
13. (c) Alum coagulates mud particles and helps in purifying water.
14. (a) On increasing temperature adsorption of a gas on surface of solid
decreases. Solid adsorb greater amount of substances at lower
temperature.
15. (a) On shaking with the dispersion medium, colloids directly form the
colloidal sol. Hence they are called intrinsic colloids. i.e., glue.
16. (d) According to Freundlich adsorption isotherm.
At intermediate pressure, extent of adsorption
 or 
plot of  vs log P is linear with slope = 
17. (b)
18. (b) When oppositely charged sols are mixed their charges
are neutralised. Both sols may be partially or completely precipitated.
19. (b) Peptisation is disintegration of colloidal aggregate.
20.     (a)     According to Langmuir's model of adsorption of a gas on a soild
surface the mass of gas adsorbed(x)per gram  of  the adsorbent
(m) is directly proportional to the pressure of the gas (p) at
constant temperature  i.e.
21. (c) The more the liquefiable nature of a gas, the more is the enthalpy
of adsorption. Water is more liquefiable.
22. (a) A catalyst speeds up both forward and backward reaction with the
same rate.
So, equilibrium constant is not affected by the presence of a catalyst at
any given temperature.
23. (c) As Sb
2
S
3
 is a negative sol, so Al
2
(SO
4
)
3
 will be the most effective
coagulant due to higher positive charge on Al (Al
3+
) – Hardy-
Schulze rule.
Page 3


1. (a) Smaller the charge on anion, lesser will be its coagulating power.
?  KBr have Br
–
 with least charge of – 1 on Br thus KBr is least
effective in coagulating Fe(OH)
3
.
2. (b)
3. (b) According to Freundlich equation.
4. (b) 1 micron µ = 10
–6
 m and 1 millimicron = 10
–7
 m.
5. (d) All are irreversible colloidal systems.
6. (d) Cetyl trimethyl ammonium bromide,
 is a cationic micelle
7. (a)
8. (c) It is due to impact of molecules of dispersion medium on the
colloidal particles.
9. (c)
10. (c) The movement towards anode shows that sol is negative. For
coagulation of negative sol. Cation with higher charge is more
effective.
11. (d)  Fe(OH)
3
 is positive sol. K
3
[Fe(CN)
6
] will provide [Fe(CN)
6
]
3–
 for
coagulation.
12. (d) Tannin used in leather industry contains negatively charged
colloidal particles.
13. (c) Alum coagulates mud particles and helps in purifying water.
14. (a) On increasing temperature adsorption of a gas on surface of solid
decreases. Solid adsorb greater amount of substances at lower
temperature.
15. (a) On shaking with the dispersion medium, colloids directly form the
colloidal sol. Hence they are called intrinsic colloids. i.e., glue.
16. (d) According to Freundlich adsorption isotherm.
At intermediate pressure, extent of adsorption
 or 
plot of  vs log P is linear with slope = 
17. (b)
18. (b) When oppositely charged sols are mixed their charges
are neutralised. Both sols may be partially or completely precipitated.
19. (b) Peptisation is disintegration of colloidal aggregate.
20.     (a)     According to Langmuir's model of adsorption of a gas on a soild
surface the mass of gas adsorbed(x)per gram  of  the adsorbent
(m) is directly proportional to the pressure of the gas (p) at
constant temperature  i.e.
21. (c) The more the liquefiable nature of a gas, the more is the enthalpy
of adsorption. Water is more liquefiable.
22. (a) A catalyst speeds up both forward and backward reaction with the
same rate.
So, equilibrium constant is not affected by the presence of a catalyst at
any given temperature.
23. (c) As Sb
2
S
3
 is a negative sol, so Al
2
(SO
4
)
3
 will be the most effective
coagulant due to higher positive charge on Al (Al
3+
) – Hardy-
Schulze rule.
24. (d) At high pressure the extent of adsorption follows zero order
kinetics.
25. (c) The critical micelle concentration is the lowest concentration at
which micelle formation appears. When surfactants are present
above that CMC, they can act as emulsifiers that will solubilise a
compound which is normally insoluble in the solvent being used.