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 k + 1/n log P Slope = 1/n log x/m intercept = log k 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. N 2 b. CO 2 c. Cl 2 d. O 2 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 Na 2 SO 4, CaCl 2, Al 2 (SO 4 ) 3 and NH 4 Cl, the most effective coagulating agent for Sb 2 S 3 sol is a. Na 2 SO 4 b. CaCl 2 c. Al 2 (SO 4 ) 3 d. NH 4 Cl 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 SO 2 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 NO 2 b. Oxidation of SO 2 to SO 3 c. Decomposition of KCIO 3 to KCI and O 2 d. Oxidation of oxalic acid by acidified KMnO 4 Ans. d
30. Given below, catalyst and corresponding process or reaction are matched. The mismatch is? a. Platinised asbestos Contact process b. TiCl 4 + Al (C 2 H 5 ) 3 - Polymerisation c. V 2 O 5 Haber process d. Nickel Hydrogenation Ans. c
31. Helium gas at 300 K is shifted from a vessel of 250 Cm 3 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: P 1 V 1 = P 2 V 2 P 1 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 N 2, O 2, H 2 and He separately, then which one will be filled first? a. N 2 b. O 2 c. H 2 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, P 1 = P, V 1 = V, T 1 = T For gas A, P 2 = 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 CO 2 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 CH 4 = mass of O 2 = w gm
44. The number of atoms in 0.1 mole of triatomic gas is: ( N A = 6.02 x 10 23 ) a. 1.806 x 10 23 b. 3.600 x 10 23 c. 1.800 x 10 22 d. 6.026 x 10 23 Ans. a
Solution: Number of atoms = number of moles x N A x atomicity = 0.1 x 6.02 x 10 23 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. d 2 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 H 2 d. N 2 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