Chemistry Chapter 6 Entry Test MCQs
51. What is the role of the forward and backward reactions in a state of chemical equilibrium?
a. The forward and backward reactions do not occur.
b. The forward reaction dominates
c. The backward reaction dominates
d. The forward and backward reactions occur at equal rates
52. Which of the following statements is true about reversible reactions?
a. They can only proceed in forward direction
b. They only occur in closed systems
c. They always go to completion.
d. They reach a state of dynamic equilibrium.
53. What does it mean if the value of the equilibrium constant (Kc) is much greater than 1?
a. The reaction favours the products
b. The reaction favours the reactants
c. The reaction is not possible.
d. The reaction is at equilibrium
54. Which of the following statements is true about the spontaneity of reversible and irreversible reactions?
a. Reversible reactions can be spontaneous or non-spontaneous
b. Reversible reactions are always spontaneous
c. Irreversible reactions can only be non-spontaneous.
d. Irreversible reactions are always spontaneous
55. What is the equilibrium constant expression for the reaction: A + B ⇌ C + D?
a. [C][D] + [A][B]
b. [𝐂][𝐃]/[𝐀][𝐁]
c. [A][B] – [C][D]
d. [𝐀][𝐁]/[𝐂][𝐃]
56. Reversible reactions are those:
a. That become spontaneous after a while
b. That contains both reactants and products in a definite proportion
c. That don’t complete
d. Both B and C
57. KP is:
a. Ionization constant
b. Equilibrium constant is terms of partial pressure
c. Reaction constant
d. Dissociation constant
58. In the reversible reaction N2 + O2 ⇌ 2NO If KC is very low
a. Reverse reaction is very fast
b. Forward reaction almost complete
c. Reverse reaction is slow than forward reaction
d. All of these
59. If we remove heat from an exothermic reaction
a. KC changes
b. Position of equilibrium changes
c. Reaction moves forward
d. All
60. Which statement is true when this closed system reaches equilibrium? N2(g)+ O2(g) ⇌ 2NO(g)
a. The N2(g) is 50% consumed
b. Pressure changes no longer occur
c. The O2(g) is 50% consumed
d. The reverse reaction stops
61. A chemical system can undergo:
a. Physical change
b. Chemical change
c. Both Physical & Chemical
d. No change
62. Kp for the given reaction H2(g) + I2(g) ⇌ 2HI(g) is 9 at certain temperature. At this temperature, at equilibrium 0.6 moles dm3 of HI and 0.4 mol of H2 is present in 2 dm3 flask. How many moles of I2 are present in the equilibrium mixture?
a. 0.1
b. 0.4
c. 0.05
d. 0.17
63. The rate at which the reaction proceed is directly proportional to the product of the active masses of the reactants is according to
a. Law of mass action
b. Le-Chatelier’s principle
c. Law of constant proportion
d. Equilibrium law
64. Which of the following principle / rule is applicable at equilibrium?
a. Le-Chatelier’s Principle
b. Law of mass action
c. Aufbau Principle
d. Hund’s Rule
Principles and Applications of KC
65. A catalyst cannot change the property of reaction:
a. Change mechanism of reaction
b. Decrease activation energy
c. Increase the enthalpy of reaction
d. Rate of forward reaction
66. When solid NH4NO3 is dissolved in a nearly saturated solution of NH4NO3, the solution becomes colder. When temperature of the solution is raised.
a. The solubility of NH4NO3 will decrease
b. H will become negative.
c. The solubility of NH4NO3 will increase
d. H will become zero
67. Solubility of weak electrolyte __ by increasing the common ion effect.
a. Remains same
b. Increases
c. First increases & decreases
d. Decreases
68. Which of the following is not buffer solution?
a. HCl + NaCl
b. CH3COOH + CH3COONa
c. H3PO4 + Na2HPO4
d. H2CO3 + NaHCO3
69. Most effective catalyst for the preparation of SO3 is:
a. SiO2 and Al2O3
b. Conc. H2SO4
c. V2O5
d. Al2O3
70. If we have 0.1 mole of CH3COOH and one mole of sodium acetate, then the pH of buffer will be:
a. 3.74
b. 4.74
c. 4.83
d. 5.74
71. Which can act as buffer?
a. Conc. NaOH
b. NH4OH and NH4Cl
c. KOH & KCl
d. Conc. H2SO4
72. Which one of the following mixtures will be a buffer when dissolved in a dm3 of water?
a. 0.3 mole of KCl and 0.3 mole of HCl
b. 0.1 mole of Ba(OH)2 and 0.2 mole of HBr
c. 0.2 mole of CH3COOH and 0.1 mole of NaOH
d. 0.4 mole of NH3 and 0.4 mole of HCl
73. Which one of the following statements is correct about the effect of a catalyst?
a. It increases the yield of product at equilibrium
b. Increases equilibrium constant of forward reaction
c. It provides an alternative route for a reaction
d. It increases the rate constant for the forward reaction but not that of the reverse reaction
74. In order to get maximum yield of NH3, all of the following are optimum conditions EXCEPT?
a. High temperature
b. High pressure
c. Use of catalyst
d. Withdrawal of NH3
75. Which of the following statements is incorrect about Henderson’s equation for acidic buffer solution?
a. pH < pKa if [Salt] < [Acid]
b. pH = pKa if [Salt] = [Acid]
c. pH = Ka if [Salt] = [Acid]
d. pH > pKa if [Salt] > [Acid]