MCQs on Kp And Kc Relationship And Characteristics Of K for NEET 2021

The equilibrium constant principle is valid only at the equilibrium condition. Equilibrium constant values are frequently quoted without units. This usually does not create any problem, since in most problems the units of K do not enter into the calculation directly. However, it must be specified whether the equilibrium constant is Kc or Kp. The equilibrium constant of a reaction varies with temperature but, at any particular temperature, it must be a constant independent of concentration or pressure at all concentrations. The equilibrium constant quantitatively indicates the effect of concentrations of reactants and products on the extent of reaction.

1. What will be the value of Kp if the Kc is 26 for a reaction, PCl5 ⇌ PCl3 + Cl2 at 25o°?

  1. 0.57
  2. 0.46
  3. 0.83
  4. 0.61

Answer: (d)

2. For which of the following reactions Kp is less than Kc?

  1. 2HI ⇌ H2 + I2
  2. N2 + O2 ⇌ 2NO
  3. N2O4 ⇌ 2NO2
  4. 2SO2 + O2 ⇌ 2SO3

Answer: (d)

3. Two moles of PCl5 were heated to 400oC in 2 litres closed vessel. At equilibrium, 40% of PCl5 was dissociated into PCl3 and Cl2. Its Kc will be

  1. 3.75 mol/L
  2. 0.533 mol/L
  3. 0.267 mol/L
  4. None of the above

Answer: (c)

4. Which of the following is not correct?

  1. large value of K indicates large amount of products
  2. small value of K indicates large amount of reactants
  3. for K < 1 amount of reactants > amount of products
  4. none of the above

Answer: (d)

5. When Q (concentration quotient) is smaller than equilibrium constant

  1. reaction will be in equilibrium
  2. reaction will proceed in forward direction
  3. reaction will proceed in backward direction
  4. none of the above

Answer: (b)

6. If Kp and Kc are in equilibrium constants in terms of partial pressure and concentration

  1. Kp = Kc/RT
  2. Kp = KcRT
  3. Kp = Kc/(RT)𐤃n
  4. Kp = Kc(RT)𐤃n

Answer: (d)

7. For a reaction in equilibrium

  1. Q (concentration quotient) = K (equilibrium constant)
  2. Q > K
  3. Q < K
  4. none of the above

Answer: (a)

8. Active mass in the law of mass action is

  1. molar concentration
  2. absolute concentration
  3. concentration at 0oC
  4. molar mass

Answer: (a)

9. The mass of a gas dissolved in a given mass of a solvent at any temperature is directly proportional to

  1. pressure of gas
  2. volume of gas
  3. density of gas
  4. none of above

Answer: (a)

10. Which of the following is an example of solid-solution equilibrium?

  1. dissolution of sugar in water
  2. melting of ice
  3. evaporation of water in a closed vessel
  4. none of the above

Answer: (a)

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