M.C.Q : Chemical Equilibrium ( 1 to 1 0 )

LEVEL – I
1. When KOH is dissolved in water, heat is evolved. If the temperature is raised , the solubility of KOH.

(A) Increases

(B) Decreases

(C) Remains the same

(D) Cannot be predicted

2. For the liquefaction of gas, the favourable conditions are

(A) Low T and high P

(B) Low T and low P

(C) Low T and high P and a catalyst

(D) Low T and catalyst

3. Consider the water gas equilibrium reaction
C(s) + H2O(g) <−−> CO(g) + H2(g)
Which of the following statement is true at equilibrium

(A) If the amount of C(s) is increased, less water would be formed

(B) If the amount of C(s) is increased, more CO and H2 would be formed

(C) If the pressure on the system is increased by halving the volume, more water would be formed.

(D) If the pressure on the system is increased by halving the volume, more CO and H2 would be formed.

4. A reaction takes place in two steps with equilibrium constants 10-2 for slow step and 102 for last step. The equilibrium constant of the overall reaction will be

(A) 104

(B) 10-4

(C) 1

(D) 10-2

5. For the reaction PCl3(g) + Cl2(g) <−> PCl5(g) ,
the value of KC at 250°C is 26 mol–1/ litre. The value of Kp at this temperature will be

(A) 0.61 atm-1

(B) 0.57 atm-1

(C) 0.85 atm-1

(D) 0.46 atm-1

6. According to Le Chatlier’s principle adding heat to a solid and liquid in equilibrium with endothermic nature will cause the

(A) Amount of solid to decrease

(B) Amount of liquid to decrease

(C) Temperature to rise

(D) Temperature to fall

7. An aqueous solution of hydrogen sulphide shows the equilibrium
H2S <−> H+ + HS–1
If dilute hydrochloric acid is added to an aqueous solution of H2S , without any change in temperature, then

(A) The equilibrium constant will change

(B) The concentration of HS–1 will increase

(C) The concentration of undissociated hydrogen sulphide will decrease

(D) The concentration of HS–1 will decrease

8. What would happen to a reversible reaction at equilibrium when temperature is raised, given that its ΔH is positive

(A) More of the products are formed

(B) Less of the products are formed

(C) More of the reactants are formed

(D) It remains in equilibrium

9. Applying the law of mass action to the dissociation of hydrogen Iodide
2HI(g) <−> H2 + I2
We get the following expression

Where a is original concentration of H2 , b is original concentration of I2 , x is the number of molecules of H2 and I2 reacted with each other. If the pressure is increased in such a reaction then

(A)

(B)

(C)

(D) none of these

10. One mole of ethanol is treated with one mole of ethanoic acid at 25°C.
One–fourth of the acid changes into ester at equilibrium. The equilibrium constant for the reaction will be

(A) 1/9

(B) 4/9

(C) 9

(D) 9/4

ANSWER:

1. (B)  2. (A)  3. (C)  4. (C)  5. (A)  6. (A)  7. (D)  8. (A)  9. (A)  10.(A)

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M.C.Q : Chemical Equilibrium ( 11 to 20 )

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