Law Of Mass Action MCQs

Another notable aspect of theoretical development was that initially, the law of mass action was referred to as the kinetic law of mass action. Chemists were keen to identify a parameter that would elucidate a compound’s reactivity and its ability to produce the desired products. Although reaction levels seemed to offer such a parameter, it proved challenging to define. Understanding the historical progression of chemical discoveries that led to the formulation of the law of mass action is crucial for grasping its current significance. The empirically established principle—that the rates of chemical reactions are proportional to the active masses of the reactants—forms the kinetic law of mass action. This principle leads to a dynamic interpretation of chemical equilibrium and consequently to the law of mass action in equilibrium.

Which of the following is not correct?

(a) The rate law is an experimental fact, but the law of mass action is theoretical
(b) The rate law is always different from the expression of the law of mass action
(c) The rate law is more informative than the law of mass action for the development of a mechanism
(d) The order of a reaction is equal to the sum of the powers of the concentration terms in the rate law.

What is the half-life of a radioactive substance if 87.5% of any given amount of the substance disintegrates in 40 minutes?

(a) 160 min
(b) 10 min
(c) 20 min
(d) 13 min 20 sec

A first-order reaction is 75% complete after 32 minutes. When was 50% of the reaction completed?

(a) 16 min
(b) 8 min
(c) 4 min
(d) 32 min

The half-life of 10g of a radioactive substance is 10 days. The half-life of 20g is

(a) 10 days
(b) 5 days
(c) 20 days
(d) 40 days

The temperature coefficient of a reaction is 2. How many times the rate of reaction increases when the temperature is increased from 30°C to 60°C?

(a) 4 times
(b) 6 times
(c) 8 times
(d) 16 times

The number of atoms or molecules whose concentration alters during a chemical change is its

(a) Molecularity
(b) Order of reaction
(c) Change in reaction
(d) None

For a reaction A → Products, the rate of reaction doubles when the concentration of A is increased by 4 times. The order of the reaction is

(a) 4
(b) 0
(c) 1/2
(d) 1

K for a zero-order reaction is 2 x 10⁻² mole/L/sec. If the concentration of the reactant after 25 sec is 0.5M, the initial concentration must have been

(a) 0.5M
(b) 1.25M
(c) 12.5M
(d) 1.0M

The chemical reactions in which reactants need a high amount of activation energy are generally

(a) Fast
(b) Slow
(c) Very fast
(d) Instantaneous

If a reaction with t₁/₂ = 69.3 sec has a rate constant of 10⁻² per sec, the order is

(a) Zero
(b) 1
(c) 2
(d) 3