Surface Chemistry

&

States of Matter

S. Sunil Kumar

Lecturer in Chemistry

1. Adsorption is

a. Colligative property

b. Oxidation process

c. Reduction process

d. Surface phenomenon

Ans. d

2. When adsorption of oxalic acid is

carried out on activated charcoal,

then activated charcoal is known as

a. Adsorbate

b. Adsorbent

c. Adsorber

d. Absorber

Ans. b

3. The process of removing an

adsorbed substance from a surface

on which it is adsorbed is called

a. Adsorption

b. Absorption

c. Desorption

d. Sorption

Ans. c

4. Adsorption increases when

a. Temperature increases

b. Temperature decreases

c. Temperature remains constant

d. None of these

Ans. b

Gas +Solid Adsorption + Heat

5. With the increase in critical

temperature of a gas, adsorption of

gas on solid

a. Increases

b. Decreases

c. May increase or decrease

d. First increases then decreases.

Ans. a ( greater the critical temperature

Of the gas, more the van der Waal's

force of attraction and more the adsorption )

6. Which adsorption takes place at

low temperature ?

a. Physical

b. Chemical

c. Both

d. None.

Ans. a ( Because Δ H is low )

7. For adsorption of a gas on a solid,

the plot of log x/m vs log P is linear

with slope equal to : ( n being whole

number)

a. K

b. log k

c. n

d. 1/n

Ans. d

log x/m

log P

Slope = 1/n

intercept = log k

log x/m = log k + 1/n log P

8. Which of the following statements is

correct about Langmuir adsorption?

a. It is reversible in nature

b. It occurs at low temperature

c. It forms monolayer

d. It is not specific in nature.

Ans. c

9. Which is adsorbed to maximum

amount by activated charcoal

a. N2

b. CO2

c. Cl2

d. O2

Ans. b

Because easily liquefiable gas adsorbed

to greater extent.

10. Which of the following is less than

zero during adsorption?

a. ∆ G

b. ∆ S

c. ∆ H

d. All the above.

Ans. d

11. Number of phases present in a

colloidal system is

a. 1

b. 2

c. 3

d. 4

Ans. b

12. Soap forms a colloidal solution in

water and removes the greasy matter

by

a. Absorption

b. Adsorption

c. Coagulation

d. Emulsification

Ans. d

13. Which one of the following is not a

colloid ?

a. Ruby glass

b. Chlorophyll

c. Haemoglobin

d. Smoke

Ans. b

14. Alum is used in the purification of

water, because

a. It is good disinfectant

b. It is a double salt

c. It precipitates the dissolved salt in

water

d. It coagulates the colloidal impurities

in water.

Ans. d

15. A liquid is found to scatter a beam

of light out leaves no residue when

passed through the filter paper. The

liquid can be described as

a. A suspension

b. A true solution

c. A colloidal sol

d. Oil

Ans. c

16. At the critical micelle concentration

(CMC) the surfactant molecules

a. Decompose

b. Associate

c. Dissociate

d. Becomes completely soluble

Ans. b

17. Lyophilic sols are more stable

than lyophobic sols because,

a. The colloidal particles have positive

charge

b. The colloidal particles have no

charge

c. The colloidal particles are solvated

d. Strong forces of attraction between

the negatively charged particles

Ans. c

18. Bredig arc method cannot be used

to prepare colloidal solution of which of

the following?

a. Pt

b. Fe

c. Ag

d. Au

Ans. Fe ( because Fe gets oxidised )

19. Peptisation is process of

a. Precipitation of colloidal particles

b. Purification of colloids

c. Dispersing precipitate in to colloids

d. Movement of colloidal particles in the

electric field.

Ans. c

20. The simplest way to check whether

a system is colloidal is by

a. Tyndal effect

b. Brownian movement

c. Electrodialysis

d. Finding out the particle size.

Ans. a

21. The basic principle of Cottrell

precipitator is

a. Le Chatelier's principle

b. Neutralisation of charge on colloids

c. Peptisation

d. None of the above.

Ans. b

22. Gold number of protective colloids

A, B, C and D are 0.50, 0.01, 0.10

and 0.05 respectively. The correct

order of their protective powers is ?

a. A < C < B < D

b. B < D < A < C

c. D < A < C < B

d. C < B < D < A

Ans. a

Hint: Smaller the gold number, greater

is the protective power.

D ( 0.005 ) > B ( 0.01 ) > C ( 0.50 ) > A (

0.50)

OR

A< C < B < D

23. Among the electrolytes Na2SO

4,

CaCl2, Al

2(SO

4)3 and NH

4Cl, the most

effective coagulating agent for Sb2S

3

sol is

a. Na2SO

4

b. CaCl2

c. Al2(SO

4)3

d. NH4Cl

Ans. c

24. A person is suffering from poisoning

due to arsenic then which one of the

following helpful in removing arsenic ?

a. Colloidal sulphur

b. Colloidal antimony

c. Colloidal sol of gold

d. Colloidal Fe(OH)3

Ans. d

25. The coagulation of 200 mL of a

positive colloid took place when 0.73 g

HCl was added to it without changing

the volume much. The flocculation

value of HCl for the colloid is

a. 0.365

b. 36.5

c. 100

d. 150

Ans. c

Solution:

200 mL of the sol require 0.73 g HCl

No. of moles of HCl =

26. The role of catalyst is only to

a. Decrease activation energy

b. Increases activation energy

c. Brings about equilibrium

d. None of these.

Ans. a

27. Which of the following kinds of

catalysis can be explained by the

adsorption theory ?

a. Homogeneous catalysis

b. Acid-base catalysis

c. Heterogeneous catalysis

d. Enzyme catalysis

Ans. c

28. Which of the following is an example of

homogeneous catalysis ?

a. Haber process of synthesis of ammonia.

b. Catalytic conversion of SO2

to SO 3

in

contact process

c. Catalytic conversion of water gas to

methanol

d. Acid hydrolysis of methyl acetate.

Ans. d

29. An example of autocatalysis is

a. Oxidation of NO to NO2

b. Oxidation of SO2 to SO

3

c. Decomposition of KCIO3 to KCI and

O2

d. Oxidation of oxalic acid by acidified

KMnO4

Ans. d

30. Given below, catalyst and

corresponding process or reaction are

matched. The mismatch is ?

a. Platinised asbestos – Contact

process

b. TiCl4 + Al (C

2 H

5 )

3 - Polymerisation

c. V2O

5 – Haber process

d. Nickel – Hydrogenation

Ans. c

31. Helium gas at 300 K is shifted from

a vessel of 250 Cm3 to a vessel of 1 L

capacity. The pressure of gas will

a. Becomes four times

b. Become double

c. Decrease to half of the original value

d. Decrease to ¼th of the original value.

Ans. d

Solution:

P1V

1 = P

2V

2

P1 x 250 = 1000 x P

2

32. The density of neon will be

maximum at

a. NTP

b. 0° C, 2 atm

c. 273° C, 1 atm

d. 273° C, 2 atm

Ans. b

Because d α p and p α 1/T

33. At what temperature would the

volume of a given mass of a gas at

constant pressure be twice its volume

at 0° C ?

a. 100° C

b. 273° C

c. 373° C

d. 546° C

Ans. b

Solution:

34. For an ideal gas, number of moles

per liter in terms of its pressure P, gas

constant R, and temperature T is

a. PT / R

b. PRT

c. P / RT

d. RT / P

Ans. c

Solution: PV = n RT

Number of moles per liter =

35. The densities of two gases are in

the ratio of 1 : 16. the ratio of their rate

of diffusion is

a. 16 : 1

b. 4 : 1

c. 1 : 4

d. 1 : 16

Ans. b

Solution:

Or 4 : 1

36. According to kinetic theory of

gases, in an ideal gas, between two

successive collisions, a gas molecules

travels

a. In a circular path

b. In a wavy path

c. In straight line

d. With an accelerated velocity

Ans. c

37. If the four tubes of a car are filled to

the same pressure with N2, O

2, H

2 and

He separately, then which one will be

filled first?

a. N2

b. O2

c. H2

d. He

Ans. c ( lower the density

faster the diffusion )

38. Containers A and B have same gas.

Pressure, volume and temperature of A

are all twice that of B. Then the ratio of

the number of molecules of A and B are

a. 1 : 2

b. 2 : 1

c. 1 : 4

d. 4 : 1

Ans. b

Solution:

For gas B, P1 = P , V

1 = V, T

1 = T

For gas A, P2 = 2 P, V

2 = 2 V, T

2 = 2 T

Applying ideal gas equation,

Or

39. 28 g of each of following gases are

taken at 27° c and 600 mm pressure.

Which of the these will have the least

volume ?

a. HBr

b. HCl

c. HF

d. HI

Ans. d

Solution:

PV = n RT or

Since P and T are same V α n

As , , n will we least for

which M is maximum.

40. By what factor does the average

velocity of a gaseous molecule

increase when the absolute

temperature doubled ?

a. 1.4

b. 2.0

c. 2.8

d. 4

Ans. a

Solution:

Average velocity

When the temperature is doubled,

41. A real gas most closely approaches

ideal gas behaviour at

a. 1.5 atm and 200 K

b. 1.0 atm and 273 K

c. 0.5 atm and 500 K

d. 15.0 atm and 500 K

Ans. C ( low pressure and high

temperature)

42. Molar volume of CO2 is maximum at

a. NTP

b. 0° C and 2.0 atm

c. 127° C and 1 atm

d. 273° C and 2.0 atm

Ans. c

43. Equal masses of methane and

oxygen are mixed in an empty container

at 25° C. The fraction of total pressure

exerted by oxygen is

a. 1/2

b. 2/3

c. 273/298

d. 1/3

Ans. d

Solution:

If the mass of CH4 = mass of O

2 = w gm

44. The number of atoms in 0.1 mole of

triatomic gas is: ( NA = 6.02 x 10

23 )

a. 1.806 x 1023

b. 3.600 x 1023

c. 1.800 x 1022

d. 6.026 x 1023

Ans. a

Solution:

Number of atoms = number of moles x

NA

x atomicity

= 0.1 x 6.02 x 1023

x 3

= 1. 806 x 10

23

45. When the temperature is increased,

the viscosity of the liquid decreases.

This is because,

a. Volume of the solution decreases

b. Average kinetic energy of molecules

increases which overcomes the

attractive forces

c. Decreases the hydrogen and covalent

bond

d. None of the above.

Ans. b

46. The r.m.s velocity of an ideal gas at

constant pressure varies with density (

d ) as

a. d2

b. d

c.

d. 1/

Ans. d

Solution:

47. Select the one having maximum

viscosity

a. Acetone

b. Ether

c. Alcohol

d. Glycol

Ans. d ( due to H-bonding )

48. At relatively high pressure, van der

Waal’s equation reduces to

a. PV = RT

b. PV = RT – a/V

c. PV = RT + Pb

d. PV = RT – a/V2

Ans. c

Solution:

At high pressure is negligible.

For one mole of gas

( P + 0 ) ( V – 0 ) = RT

PV = RT + Pb

49. Dalton’s law of partial pressure is

not applicable to which of the

following gaseous mixtures ?

a. Nitrogen and oxygen

b. Nitric oxide and oxygen

c. CO and H2

d. N2 and H

2

Ans. b ( Dalton’s law is applicable to

mixture of non reacting gases )

50. In the van der Waal’s equation of

state about gas laws, the constant b

is measure of ?

a. Intermolecular collisions per unit

volume

b. Intermolecular attraction

c. Volume occupied by the molecules

d. Intermolecular repulsion

Ans. c

51. If the temperature of an ideal gas in

sealed, rigid container is increased to

1.5 times the initial value ( in K ), the

density of the gas

a. Becomes 1.5 times the initial value

b. Becomes 1/1.5 times the initial value

c. Becomes 2.5 times the initial value

d. Remains constant

Ans. d ( because mass and volume

remains constant )

52. An ideal gas cannot be liquefied

because,

a. Its critical temperature is always

above 0° C-

b. Its molecules are smaller in size

c. It solidifies before becoming liquid.

d. Force of attraction between its

molecules are negligible.

Ans. d