• 1. The role of catalyst in a reversible reaction is

    • a) to start the forward reaction
    • b) to start both forward and backward reactions
    • c) to stop the forward and backward reactions
    • d) to attain the state of equilibrium in less time
    A catalyst can, neither start the reaction nor stop the reaction. It can make the system to attain equilibrium quickly.
  • 2. Reaction between neutral solution of barium chloride and sodium carbonate goes to completion because

    • a) A gas is formed 
    • b) The reaction is reversible 
    • c) Barium carbonate is insoluble 
    • d) Sodium chloride is more stable than sodium carbonate 
    In the above reaction barium carbonate (BaCO3) and sodium chloride are formed. But barium carbonate is an insoluble precipitate. It cannot undergo reverse reaction.
  • 3. Which of the following reactions illustrate the irreversible reaction ?
    a) BaCl2+Na2SO4→BaSO4+2NaCl
    b) 3Fe+4H2O→Fe3O4+4H2
    c) 2KClO3→2KCl+3O2
    d) Pb(NO3)2+2Nal→PbI2+2NaNO3.

    • a) only (a)
    • b) (a) and (d)
    • c) (a) and (c)
    • d) (a) and (b)
    Equations (a) and (d) are irreversible as one of the products BaSO4 and Pbl2 respectively are solid precipitate which do not give back the reactants.
  • 4. Statement–1: The equilibrium constant for a reaction having positive ΔH° increases with increase of temperature.
    Statement–2: The temperature dependence of the equilibrium constant is related to ΔS° and not ΔH° for the reaction.

    • a) Statement–1 is True, Statement–2 is True; Statement–2 is correct explanation for Statement–1
    • b) Statement–1 is True, Statement–2 is True; Statement–2 is not a correct explanation for Statement–1
    • c) Statement–1 is True, Statement–2 is False
    • d) Statement–1 is False, Statement–2 is True
    ΔH° is positive indicates an endothermic reaction. With increase in temperature, endotherimic reaction are favoured hence equilibrium constant for such a reaction increases with increase in temperature. The temperature dependence of the equilibrium constant is related to ΔH° of the reaction
  • 5. Which of the following changes can be reversed?

    • a) Raw egg to boiled egg
    • b) Wet clothes to dry clothes
    • c) Bud to flower
    • d) Cow dung to biogas
    We can wet a dry cloth. In the reverse, a wet cloth can be dried. So, the cycle of drying and wetting or vice versa is reversible.