CBSE Class 11 Chemistry Chemical Equilibrium MCQs

I. MCQ - Choose Appropriate Alternative

1. At equilibrium the rate of forward reaction and the rate of reverse reaction are __________. (Equal, Changing, Different)

2. Such reactions, which proceed to forward direction only and are completed after sometime are called __________ reaction. (Irreversible, Reversible, Molecular)

3. Such reactions, which proceed to both the direction and are never completed, are called __________ reaction. (Irreversible, Reversible, Molecular)

4. The rate of chemical reaction is directly proportional to the product of the molar concentration of __________. (Reactants, Products, Both reactants and products)

5. “If a system in equilibrium is subjected to a stress, the equilibrium shifts in a direction to minimize or undo the effect of this stress. This principle is known as __________. (Le-Chatelier’s Principle, Gay Lussac’s Principle, Avogadro’s Principle)

6. A very large value of K_c indicates that reactants are __________. (very stable, unstable, moderately stable)

7. A very low value of K_c indicates that reactants are __________. (very stable, very unstable, moderately stable)

8. The equilibrium in which reactants are products are in single phase is called __________. (Homogenous Equilibrium, Heterogenous Equilibrium, Dynamic Equilibrium)

9. The equilibrium in which reactants and products are in more than one phases are called __________. (Homogenious Equilibrium, Heterogenious Equilibrium, Dynamic Equilibrium)

10. Chemical Equilibrium is __________ equilibrium. (Dunamic, Static, Heterogeneous)

11. In exothermic reaction, lowering of temperature will shift the equilibrium to __________. (right, left, equally on both the direction)

12. In endothermic reaction, lowering of temperature will shift the equilibrium to __________. (right, left, equally on both the direction)

13. A catalyst __________ the energy of activation. (increases, decreases, has no effect on)

14. At equilibrium point __________. (forward reaction is increased, backward reaction is increased, forward and backward reactions become equal)

15. NH₃ is prepared by the reaction N₂ + 3H₂ → 2NH₃ ; ΔH = -21.9 Kcal. The maximum yield of NH3 is obtained __________. (At low temperature and high pressure, at high temperature and low pressure, at high temperature and high pressure)

16. When a high pressure is applied to the following reversible process: N₂ + O₂ →2NO The equilibrium will __________ (shift to the forward direction, shift to the backward direction, not change)

17. The value of Kc __________ upon the initial concentration of the reaction. (depends, partially depends, does not depend)

18. While writing the Kc expression, the concentration of __________ are taken in the numerator.

19. Solubility product constant is denoted by __________. (Kc, Ks_p, Kr)

20. “The degree of ionization of an electrolyte is suppressed by the addition of another electrolyte containing a common ion.” This phenomenon is called __________. (Solubility Product, Common Ion Effect, Le-Chatelier’s Principle)

II. Fill in the Blanks

1. The reactions, which proceed in both the directions, are called __________ reactions.

2. The reactions, which proceed to one direction only, are called __________ reactions.

3. Reversible reactions are __________ completed.

4. Irreversible reactions are __________ after some time.

5. A reversible reaction is said to be in __________ when the rate of forward reaction becomes equal to the rate of backward reaction.

6. The concentrations of reactants and products are __________ at equilibrium point.

7. The value of Kc depends upon the __________ of the reactants.

8. A increase of the value of Kc tends to move the reaction to the __________ direction.

9. A decrease of the value of Kc tends to move the reaction to the __________ direction.

10. An increase in the concentration of the reactants will move the reaction to the __________ direction.

11. A decrease in the concentration of the reactants will move the reaction to the __________ direction.

12. Equilibrium constant is denoted by __________.

13. When the equilibrium constant value is very __________, we can conclude that the forward reaction is almost completed.

14. When equilibrium constant value is very __________ we can conclude that forward reaction will occur to very little extent.

15. According to __________ principle, if system in equilibrium is subjected to a stress, the equilibrium shifts in a direction to minimize or undo the effect of the stress.

16. In exothermic reaction, the __________ of temperature favour the forward rate of reaction.

17. In endothermic reactions, the __________ of temperature favour the forward rate of reaction.

18. A __________ is a substance which effects the rate of reaction but remains unaltered at the end of the reaction.

19. A catalyst increases the velocity of the reaction by decreasing the __________.

20. The suppression of degree of ionization of a sparingly soluble weak electrolyte by the addition of a strong electrolyte containing an ion in common is called __________.

21. __________ is purified in industries by Common Ion Effect.

22. A reaction moves to the left when the concentrations of the products are __________.

23. A reaction moves to the right when the concentrations of the products are __________.

24. Increase in pressure will move the reaction in the direction of __________ volume.

25. Decrease in pressure will move the reaction in the direction of __________ volume.

26. An increase of temperature favours the formation of products in case of __________ reaction.

27. A decrease of temperature fovours the formation of products in case of __________ reaction.

28. Heating moves an endothermic reaction to the __________.

29. Cooling move an exothermic reaction to the __________.

30. The product of ionic concentration in a saturated solution is called __________ constant.

31. When HCl is added to NaCl, the concentration of __________ ion is increased.

32. Chemical reaction involving the substances in more than one phases are called __________.

33. The formation of NH₃ is exothermic process hence __________ temperature will favour the formation of NH₃.

34. The formation of NO from N₂ and O₂ is endothermic process hence __________ temperature will favour the formation of NO.

35. Chemical Equilibrium is __________ equilibrium.

36. Molar concentration is also called __________.

37. The rate at which a substance takes part in a chemical reaction depends upon its __________.

38. __________ principle is applied to all reversible reaction.

39. A common ion __________ the solubility of the salt.

40. Number of moles present per dm3 of a substance is called __________.