Question

The rate at which a substance reacts depends upon its __________.
A. Active mass
B. Molecular mass
C. Atomic mass
D. Equivalent mass

Answer 1

Hint:
Rate of reaction is defined as the speed at which molecules react with each other and form the products or the speed at which a chemical reaction takes place. It depends on the law of mass actions.

Complete step by step answer:
The law of mass action states that the rate of the reaction depends mainly on the concentrations of the reactants. More is the concentration of reactants, more is the rate of reaction.
Now, let us look at what the terms given in the options really mean:
A) Active mass: It is the mass of the reactants that actually take part in the reaction that is taking place. It is also called the reactive mass.
B) Molecular mass: It is the mass each molecule has in atomic units.
C) Atomic mass: It is the mass of each atom involved in the reaction.
D) Equivalent mass: It is the mass of any substance that corresponds to the number of electrons exchanged in the reaction.
Here, we can see that the only term that is related to how many molecules are involved in the reaction is the term ‘Active mass’. The active mass of the reactants will determine the concentration.

Hence, the correct answer to this question is ‘A. Active mass’.

Note:
The rate of the reaction depends not only on the concentration of the reactants but also other factors like temperature, energy, etc. The main factor that the reaction depends on is the concentration.