This set of Class 11 Chemistry Chapter 7 Multiple Choice Questions & Answers (MCQs) focuses on “Equilibrium in Physical Processes”.
1. If both the forward and reverse reaction rates are equal in the equilibrium is said to be ____________
a) dynamic equilibrium
b) equilibrium mixture
c) static equilibrium
d) newton equilibrium
Explanation: When the reactants are kept in a closed vessel at a certain temperature the concentration of reactants keep on decreasing while the concentration of products keep on increasing, at this stage when the rate of both the forward and the reverse reactions become equal, it is said to be in a dynamic equilibrium.
2. Physical equilibrium is the same as the chemical equilibrium.
Explanation: Equilibrium that is set up in a physical process like the evaporation of water melting of solids is called physical equilibrium. If a reversible reaction is carried out in a closed vessel chemical equilibrium occurs when the rate of both the forward and backward reactions are equal, so the above statement is false.
3. Which of the following characteristics of chemical equilibrium is true?
a) equilibrium is dynamic in nature
b) equilibrium cannot be attained from either side
c) equilibrium cannot be obtained in a closed container
d) equilibrium state is affected by the presence of a catalyst
Explanation: The correct statements of the wrong ones are; equilibrium can be attained from another side, the catalyst does not affect the equilibrium state and it can only be achieved in a closed container. Therefore equilibrium is dynamic in nature is the true characteristic of chemical equilibrium in the given options.
4. Which of the following is an example of solid-liquid equilibrium?
a) water and steam at hundred degrees centigrade
b) water and ice at 0-degree centigrade
c) the point where Ammonia is sublimized
d) boiling point of water
Explanation: At zero degree centigrade, when water and ice are together the opposing process occurs simultaneously at the same rate, so the amount of Ice and water remains constant. It is an example of a solid-liquid equilibrium.
5. Amount of a gas that is dissolved in a solvent depends on the pressure of the solvent.
Explanation: The most common form of Henry’s law states that the partial pressure of the gas in the vapor phase is proportional to the mole fraction of the gas in a solution, therefore we can say that the above-given statement is true.
6. Which of the following statements is false regarding the equilibrium constant?
a) it has a definite value for every chemical reaction at a particular temperature
b) it is independent of initial concentrations of the reactants
c) it is dependent on the presence of a catalyst
d) if K is the equilibrium constant for a backward reaction then the forward reaction’s equilibrium constant is 1/k
Explanation: Equilibrium constant is independent of the presence of a catalyst, so the statement regarding the catalyst is wrong. A catalyst helps reaction to attain its equilibrium faster but does not alter the equilibrium constant.
7. What will happen if the rate of evaporation is equal to the rate of condensation in the water?
a) solid-liquid equilibrium
b) liquid-vapor equilibrium
c) solid-vapor equilibrium
Explanation: When the rate of evaporation is equal to the rate of condensation water in the liquid phase and steam in vapor phase remained at equilibrium because its forward rate of the reaction and the backward rate of the reaction is the same at this particular temperature.
8. The equilibrium in a chemical reaction is represented by the symbol ____________
Explanation: The symbol that has both the left-sided harpoon and right-sided harpoon together is a symbol used for the equilibrium in a chemical reaction. It denotes that the backward and the forward rates are equal and is represented by the symbol “\(\rightleftharpoons\)”.
9. Select the correct equilibrium involving physical equilibrium.
a) it is possible only in a closed system at a given temperature
b) both forward and backward does not occur at the same rate
c) there is a dynamic but an unstable condition
d) measurable properties of the system do not remain constant
Explanation: The corrected statements of the wrong ones are that both backward and forward reactions occur at the same rate in a stable condition, while the measurable properties of the system remain constant.
10. When solid sugar dissolves in the solution __________ equilibrium is attained.
a) liquid vapor
b) solid liquid
c) solid vapor
Explanation: When sugar, which is in solid form dissolves in a solvent, forming sugar solution – a solid-liquid equilibrium is formed, where the rate of dissolution of sugar is equal to the rate of crystallization of sugar.
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