1. When rate of forward reaction becomes
equal to backward reaction, this state is termed as
(a) Chemical equilibrium
(b) Reversible state
(c) Equilibrium
(d)
All of these
Ans-a
2. In chemical reaction A ⇌ B , the system will be known in equilibrium when
(a)
A completely changes to B
(b) 50% of A changes to B
(c) The rate of change of A to B and B to A
on both the sides are same
(d) Only 10% of A changes to B
Ans-c
3.
In the chemical reaction N2 + 3H2 ⇌ 2NH3 at
equilibrium point, state whether
(a) Equal volumes of N2 and H2 are reacting
(b)
Equal masses of N2 and H2 are reacting
(c)
The reaction has stopped
(d) The same amount of ammonia is formed as
is decomposed into N2 and H2
Ans-d
4. In the reversible reaction A +B⇌ C+ D , the concentration of each C and D at equilibrium was 0.8
mole/litre, then the equilibrium constant Kc will be
(a)
6.4
(b)
0.64
(c) 1.6
(d) 16.0
Ans-d
5. For the reaction A + 2B ⇌ C , the expression for equilibrium constant is
(a) [C] [A][B] 2
(b) [C] [A][B]
(c) [A][B] /[C]2
(d) [C]
/2[B][A]
Ans-c
6. For the reaction 2SO2 + O2 ⇌ 2SO3 , the units of Kc are
(a) litre mole--1
(b) mol litre-1
(c) (mol litre-1 ) 2
(d) (litre mole-1 ) 2
Ans-a
7. The equilibrium concentration of X, Y
and YX2 are 4, 2 and 2 moles respectively for the equilibrium 2X+ Y ⇌ YX2. The value of Kc is
(a) 0.625
(b) 0.0625
(c) 6.25
(d) 0.00625
Ans-b
8. For the reaction H2+ I2 ⇌ 2HI ,the equilibrium concentration of H2 ,I2 and HI are 8.0, 3.0 and 28.0 mol per litre respectively, the equilibrium constant of the reaction is
(a) 30.66
(b) 32.66
(c) 34.66
(d) 36.66
Ans-b
9. The rate of forward reaction is two
times that of reverse reaction at a given temperature and identical
concentration. Kequilibrium is
(a) 2.5
(b) 2.0
(c) 0.5
(d) 1.5
Ans- b
10. 3.2 moles of hydrogen iodide were
heated in a sealed bulb at 444 C o till the equilibrium state was reached. Its
degree of dissociation at this temperature was found to be 22%. The number of
moles of hydrogen iodide present at equilibrium are
(1) 2.496
(2) 1.87
(3)
2
(4) 4
(a) 2.496
(b) 1.87
(c) 2
(d)
4
Ans-a
11. The reaction, 2SO2 (g) + O2 (g) ⇌ 2SO3 (g) is carried out in a 1 dm3 vessel and 2 dm3 vessel separately. The ratio of the reaction velocities will be
(a) 1: 8
(b) 1: 4
(c) 4 :1
(d) 8 :1
Ans-a
12. For the reaction : H2(g) + CO2(g) ⇌ CO(g) + H2O(g) , if the initial concentration of [H2 ] = [CO2 ] and x moles/litre of hydrogen is consumed at equilibrium, the correct expression of Kp is
(a) x 2 /(1- x)2
(b) (1+ x)2 /(1- x)2
(c) x 2 /(2 + x)2
(d) x 2 /1 - x 2
Ans-d
13 In which of the following reaction Kp > Kc
(a) N2 + 3H2 ⇌ 2NH3
(b) H2 + I2⇌ 2HI
(c) PCl3 + Cl2 ⇌ PCl5
(d) 2SO3 ⇌ O2 + 2SO2
Ans-d
14. For the reaction PCl5 (g) ⇌ PCl3 (g) + Cl2 (g)
(a) Kp = Kc
(b) Kp = Kc (RT)-1
(c) Kp = Kc (RT)
(d) Kp = Kc (RT)2
Ans-c
15. The equilibrium
constant (Kp ) for the
reaction PCl5 (g) ® PCl3 (g) + Cl2 (g) is 16. If the volume of the container is reduced to one
half its original volume, the value of Kp temperature
will be for the reaction at the same
(a) 32
(b)
64
(c) 16
(d) 4
Ans-c
16. Some solid NH4 HS is placed in a flask containing 0.5 atm of NH3 , what would be pressures of NH3 and H 2 S when equilibrium is reached NH4 HS(g) ⇌ NH3(g) + H2S(g) , Kp = 0.11
(a) 6.65 atm
(b) 0.665 atm
(c) 0.0665 atm
(d) 66.5 atm
Ans-b
17. The chemical equilibrium of a reversible reaction is not
influenced by
(a) Pressure
(b) Catalyst
(c) Concentration
of the reactants
(d) Temperature
Ans-b
18. For the reaction, CO(g) + Cl2(g) ⇌ COCl2(g the Kp / Kc is equal to
(a) √RT
(b) RT
(c) 1/ RT
(d) 1.0
Ans-c
19. What is the effect of increasing pressure on the
dissociation of PCl5 according to the equation PCl5(g) ⇌ PCl3(g) + Cl2(g) - x cal
(a) Dissociation decreases
(b) Dissociation increases
(c) Dissociation
does not change
(d) None of these
Ans-a
20. If equilibrium constants of
reaction, N2 + O2 ⇌ 2NO is K1 and 1/2 N2 + 1/2 O2 ⇌ NO is K2 , then
(a) K1 = K2
(b) K1 = √ K2
(d) K1 = 1/ 2 K2
Ans- b
21. In an equilibrium reaction for which DG0 = 0 , the equilibrium constant K =
(a) 0
(b) 1
(c) 2
(d) 10
Ans-b
22. N2 + O2 ⇌ 2NO - Q
In the above reaction which is the essential condition for the
higher production of NO
(a) High temperature
(b) High
pressure
(c) Low temperature
(d) Low pressure
23. Which of the following reactions proceed at low pressure
(a) N2 + 3H2 ⇌ 2NH3
(b) H2 + I2
⇌ 2HI
(c) PCl5 ⇌ PCl3 + Cl2
(d) N2 + O2 ⇌ 2NO
Ans-c
24. The reaction A + B⇌ C + D +heat has
reached equilibrium. The reaction may be made to proceed forward by
(a) Adding more C
(b) Adding more D
(c) Decreasing the temperature
(d) Increasing the temperature
Ans- d
25. pH of a 10 M solution of HCl is
(a) Less than 0
(b) 2
(c) 0 (d) 1
Ans-c
26. The solution of Na2CO3 has pH
(a) Greater than 7
(b) Less than 7
(c) Equal to 7
(d) Equal to zero
Ans-a
27. The hydrogen ion concentration of
0.001 M NaOH solution is
(a) 1´10-2 mole / litre
(b) 1´10-11mole / litre
(c) 1´10-14mole / litre
(d) 1´10-12mole / litre
Ans-
28. A week monoprotic acid of 0.1 M, ionizes to 1% in solution. What will be the pH of
solution ?
(a) 1
(b) 2
(c) 3
(d) 11
Ans-
29. The pH of millimolar HCl is
(a)1
(b) 3
(c) 2
(d) 4
Ans-
30. Which of the following
statement(s) is(are) correct
(a) The pH of 1.0 ´10-8 M solution of HCl is 8
(b) The conjugate base of H2PO4- is HPO42-
(c) Autoprotolysis constant of
water increases with temperature
(d) When a solution of a weak
monoprotic acid is titrated against a strong base, at half neutralization
point pH = 1 pKa
Ans-
31. In any chemical reaction, equilibrium is supposed to be establish when
(a) Mutual opposite reactions undergo
(b) Concentration of reactants and resulting products are equal
(c) Velocity of mutual reactions become equal
(d) The temperature of mutual opposite reactions become equal
Ans-
32. In a reaction the rate of reaction is proportional to its active mass, this statement is known as
(a) Law of mass action
(b) Le-chatelier principle
(c) Faraday law of electrolysis
(d) Law of constant proportion
Ans-
33. 4 moles of A
are mixed with 4 moles of B. At equilibrium for the reaction A + B⇌C + D , 2 moles of
C and D are formed. The equilibrium
constant for the reaction will be
(a) 1
(b) 41
(c) 1
(d) 42
Ans-
34. Partial pressures of A,
B, C and D on the basis of gaseous system A + 2B ⇌ C + 3D
= 0.10; C = 0.30 and D = 0.50
atm. The numerical value of equilibrium constant is (a) 11.25
(b) 18.75
(c) 5
(d) 3.75 are A =
0.20; B
Ans-
35. 2 moles of PCl5 were heated in a closed vessel of 2 litre capacity. At equilibrium, 40% of PCl5 is dissociated into PCl3 and Cl2 . The value of equilibrium constant is
(a) 0.266
(b) 0.53
(c) 2.66
(d) 5.3
Ans-
36. The decomposition of N2O4 to NO2 is carried out at 280K in
chloroform. When equilibrium has been established, 0.2 mol of N2O4 and 2 ´10-3 mol of NO2 are present in 2
litre solution. The equilibrium
constant for reaction N2O4 ⇌ 2NO2 is
(a) 1´10-2
(b) 2 ´10-3
(c) 1´10-5
(d) 2 ´10-5
Ans-
37. In a reaction
A + B⇌ C + D , the
concentrations of A, B, C and D (in
moles/litre) are 0.5, 0.8, 0.4 and 1.0 respectively. The equilibrium constant
is
(a) 0.1
(b) 1.0
(c)
10
(d) ¥
Ans-
38. If in the reaction N2O4 = 2NO2 ,a is that part of N2O4 which
dissociates, then the number of moles at equilibrium will be
(a)
3
(b) 1
(c) (1- a)2
(d) (1+ a)
Ans-
39. A quantity of
PCl5 was heated in a 10 litre vessel at 250o C;
PCl5 (g) ⇌ PCl3 (g) + Cl2 (g) . At equilibrium the vessel contains 0.1
mole of equilibrium constant of the reaction is PCl5 0.20 mole of PCl3 and 0.2 mole of Cl2 .
The
(a) 0.02
(b) 0.05
(c) 0.04
(d) 0.025
Ans-
40. A mixture of 0.3 mole of H2 and 0.3 mole of I2 is allowed to react in a 10 litre evacuated
flask at 500o C . The reaction is equilibrium
is
H2 + I2 ⇌2HI , the K is
found to be 64. The amount of unreacted I2 at
(a) 0.15 mole
(b) 0.06 mole
(c) 0.03 mole
(d) 0.2 mole
Ans-
41. In a chemical equilibrium, the
rate constant of the backward reaction is equilibrium constant is 1.5. So the
rate constant of the forward reaction is
(a) 5´10-4
(b) 2 ´10-3
(c) 1.125 ´10-3
(d) 9.0 ´10-4
Raising the temperature of an equilibrium system
(a) Favours the exothermic reaction only
(b) Favours the endothermic reaction only
(c) Favours both the exothermic and endothermic reactions
(d) Favours neither the exothermc nor endothermic reactions
Ans-b
42. The endothermic reaction (M + N D P) is allowed to attain an equilibrium at 250C . Formation of P can be increased by
(a) Raising temperature
(b) Lowering temperature
(c) Keeping temperature constant
(d) Decreasing the concentration of M and N
Ans-a
43. In the manufacture of NH3 by Haber's process, the condition which would give maximum yield is N2 + 3H2 ⇌ 2NH3 Q-kcal 3
(a) High temperature, high pressure and high concentrations of the reactants
(b) High temperature, low pressure and low concentrations of the reactants
(c) Low temperature and high pressure
(d) Low temperature, low pressure and low concentration of H2
Ans-c
44. For the reaction PCl5 (g) ⇌ PCl3 (g) Cl2 (g) , the forward reaction at constant temperature is favoured by
(a) Introducing an inert gas at constant volume
(b) Introducing chlorine gas at constant volume
(c) Introducing an inert gas at constant pressure
(d) Decreasing the volume of the container
Ans-c
45. According to Le-Chatelier's principle, which of the following factors influence a chemical system
(a) Concentration only
(b) Pressure only
(c) Temperature only
(d) Concentration, pressure and temperature
Ans-d
46. Formation of SO3 takes place according to the reaction 2SO2 + O2 ⇌ 2SO3 ; D H= 45.2kcal Which of the following factors favours the formation of SO3 ?
(a) Increase in temperature
(b) Increase in pressure
(c) Removal of oxygen
(d) Increase in volume
Ans-b
47. For the chemical reaction 3X(g) + Y(g) ⇌ X3Y(g) , the amount of X3Y at equilibrium is affected by
(a) Temperature and pressure
(b) Temperature only
(c) Pressure only
(d) Temperature, pressure and catalyst
Ans-a
48. Which of the following information can be obtained on the basis of Le-chatelier's principle
(a) Entropy change in a reaction
(b) Dissociation constant of a weak acid
(c) Equilibrium constant of a chemical reaction
(d) Shift in equilibrium position on changing value of a constant
Ans- d
49. Under what conditions of temperature and pressure the formation of atomic hydrogen from molecular hydrogen will be favoured most
(a) High temperature and high pressure
(b) Low temperature and low pressure
(c) High temperature and low pressure
(d) Low temperature and high pressure
Ans-c
50. The gaseous reaction A + B ⇌ 2C + D; + Q is most favoured at
(a) Low temperature and high pressure
(b) High temperature and high pressure
(c) High temperature and low pressure
(d) Low temperature and low pressure
Ans-d
51. Le-Chatelier’s principle is applicable only to a
(a) System in equilibrium
(b) Irreversible reaction
(c) Homogeneous reaction
(d) Heterogeneous reaction
Ans-
52. According to Le–Chatelier’s principal adding heat to a solid and liquid in equilibrium with endothermic nature will cause the
(a) Temperature to rise
(b) Temperature to fall
(c) Amount of solid to decrease
(d) Amount of liquid to decrease
Ans-
53. On addition of an inert gas at constant volume to the reaction N2 + 3H2 ⇌ 2NH3 at equilibrium
(a) The reaction remains unaffected
(b) Forward reaction is favoured
(c) The reaction halts
(d) Backward reaction is favoured
Ans-
54. The reaction 2SO2 +O2⇌ SO3 2 ; DH = – ve is favoured by
(a) Low temperature, low pressure
(b) Low temperature, high pressure
(c) High temperature, high pressure
(d) High temperature, low pressure
Ans-
55. Which of the following will favour the reverse reaction in a chemical equilibrium
(a) Increasing the concentration of the reactants
(b)Removal of at least one of the products at regular intervals
(c) Increasing the concentration of one or more of the products
(d) Increasing the pressure
Ans-
56. A2(g) + B2(g) ⇌ 2AB(g) ; DH = +ve
(a) Unaffected by pressure
(b)It occurs at 1000 pressure
(c) It occurs at high temperature
(d) It occurs at high pressure and high temperature
Ans- b
57. A physician wishes to prepare a buffer solution at pH = 3.85 that efficiently resists changes in pH yet contains only small concentration of the buffering agents. Which of the following weak acids together with its sodium salt would be best to use?
(a) 2, 5-Dihydroxy benzoic acid (pKa = 2.97)
(b) Acetoacetic acid (pKa = 3.58)
(c) m-Chlorobenzoic acid (pKa = 3.98)
(d) p-Chlorocinnamic acid (pKa = 4.41)
Answer: (b) Acetoacetic acid (pKa = 3.58)
Explanation:
For small concentration of buffering agent and for maximum buffer capacity
[Salt]/ [Acid] ≈ 1
i.e., pH = pKa
Which of the following oxides is not expected to react with sodium hydroxide?
(a) CaO
(b) SiO2
(c) BeO
(d) B2O3
Ans-a
58. A weak acid HX has the dissociation constant 1 × 10-5 M. It forms a salt NaX on reaction with alkali. The degree of hydrolysis of 0.1 M solution of NaX is
(a) 0.0001%
(b) 0.01%
(c) 0.1%
(d) 0.15%
Ans
59. When equal volumes of 0.1 M NaOH and 0.01 M HCl are mixed, the hydroxide ion concentration is
(a) 7.0
(b) 1.04
(c) 12.65
(d) 2.0
Answer: (c) 12.65
Explanation:
When equal volumes of 0.1 M NaOH and 0.01 M HCl are mixed, the hydroxide ion concentration is
(0.1 – 0.01)/(2)
= 0.045 M
The pOH of the solution is pOH = −log [OH–]
= −log 0.045
= 1.35
The pH of the solution is pH = 14 − pOH
= 14 − 1.35
= 12.65
60. Among the following the weakest Bronsted base is
(a) F–
(b) Cl–
(c) Br–
(d) I–
Ans- d
61. What is the pH of a 0.10 M solution of barium hydroxide, Ba (OH)2?
(a) 11.31
(b) 11.7
(c) 13.30
(d) None of these
Ans-Answer: (c) 13.30
Explanation:pH =13.30
Barium hydroxide is a strong base for both stages of dissociation:
Ba (OH)2(s) → Ba2+ + 2OH–
So the solution will have 0.20 M hydroxide ions. Now use the auto dissociation product for water:
[H+][OH–] = 1.0×10-14M
[OH–] = 2.0 × 10-1M
[H+] = 5.0 × 10-14M
And then pH = −log10 ([H+] = 5.0 × 10-14)
(a) 1.7 × 10-6
(b) 1.7 × 10-16
(c) 1.7 × 10-18
(d) 1.7 × 10-12
Let ”s“ be the solubility of salt M2S which undergoes dissociation as follows :-
M2S ⇌ 2M+ +S-2
Initial concentration 1 0 0
Concentration at equilibrium 1-s 2s s
Hence, the solubility product (Ksp) = (s) × (2s)²
Therefore, Ksp = 4 × s³
Or Ksp = 4× (3.5×10-6)³
⇒ Ksp
= 1.7 × 10-16
63. The strongest base from the
following species is
(a) NH-2
(b) OH-
(c) O2-
(d) S-2
64. Which one is Lewis acid
(a) Cl -
(b) Ag +
(c) C2H5OH
(d) S 2-
65. The conjugate acid of S2O82- is
(a) H2S2O8
(b) H2SO4
(c) HSO4-
(d) HS2O8-
66. Conjugate base of NH3
is
(a) NH4+
(b) NH2-
(c) NH2
(d) N2
67.. An aqueous solution of
aluminium sulphate would show
(a) An acidic reaction
(b) A neutral reaction
(c) A basic reaction
(d) Both acidic and basic
reaction
68. What will be the sum of pH and pOH in an aqueous solution
?
(a) 7
(b) pKw
(c) Zero
(d) 1
69. pH of a solution is 5. Its hydroxyl ion concentration is
(a) 5
(b) 10
(c) 5 10-
(d) 9 10-
70. The pH of a solution in which the [H ] =
0.01, +
is
(a) 2
(b) 1
(c) 4
(d) 3
71. The pH of 10-7 M NaOH is
(a) 7.01
(b) Between 7 and 8
(c) Between 9 and 10
(d) Greater than 10
Ans-b
72. 20ml of 0.5NHCl and 35ml of 0.1NNaOH are mixed. The
resulting solution will
(a) Be neutral
(b) Be basic
(c) Turn phenolphthalein solution pink
(d) Turn methyl orange red
Ans- c
(a) 3
(b) 8
(c) 11
(d) 14
Explanation:
ka kb = kw
kb = 10-8
ka × 10-8 = 10-14
ka = 10-6 = [H+]
pH = −log [H+]
pH = −log 10-6
= 6pH + pOH
= 14 pOH
= 14−6
= 8
Answer: (d) Be(OH)2
Explanation:
Be(OH)2 has the lowest value of Ksp at ordinary temperature because Be2+ ion is smaller than the other metal ions in the group, which results in a tighter bond with the 0H– ions, thus much lower solubility. The solubility of a hydroxide of group 2 elements increases down the group because as you go down the group size of metal increases thereby increasing the bond length and decreasing bond energy.
75. Which of the following aqueous solutions will have highest pH?
(a) NaCl
(b) CH3COONa
(c) Na2CO3
(d) NH4Cl
Answer: (c) Na2CO3
Explanation:
NaCl is salt of strong acid and strong base so it has pH of about 7.
NH4Cl is salt of strong acid and weak base so it has pH is much less than 7.
CH3COONH4 is salt of weak acid and weak base so it has pH of about 7.
Na2CO3 is salt of weak acid and strong base so it has pH is much greater than 7.
75. Amines behave as
(a) Lewis Acids
(b) Lewis Base
(c) Aprotic Acid
(d) Neutral Compound
Ans- b
76. Calculate the pH of the solution in which 0.2M NH4Cl and o.1M are present. the Kb of ammonia solution is 4.75.
a. 7
b. 8
c. 8.95
d. 9
ans- c
77. Calculate the pH of a 1.0 x 10-8 M solution of HCl-
a. 6.98
b. 7
c. 9
d.6
Ans- a
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