Read the passage given below and answer based it.

The rate of a reaction is concerned with decrease in concentration of reactants or increase in concentration of products per unit time. It can be expressed as instantaneous rate at a particular instant of time and average rate over a large interval of time. A number of factors such as temperature, concentration of reactants, catalyst, affect the rate of a reaction. Mathematical representation of rate of a reaction is given by rate law. It has to be determined experimentally and cannot be predicted. Order of a reaction with respect to a reactant is the power of its concentration which appears in the rate law equation. Molecularity is defined only for an elementary reaction. Molecularity and order of an elementary reaction are same.

Given below is a biomolecular elementary reaction.

\(2HI \longrightarrow H_2 + I_2\)

The order of the above reaction is

2

The correct answer is option 3. 2.

The order of a reaction is determined by the sum of the exponents in the rate equation, which are the coefficients of the reactants in the balanced chemical equation.

In the given reaction \(2HI \longrightarrow H_2 + I_2\), the rate equation is not explicitly given, but we can infer the order by looking at the coefficients in the balanced equation.

For the given reaction:

\(2HI \longrightarrow H_2 + I_2\)

The reaction is second order with respect to \(\text{HI}\) because the change in concentration of \(\text{HI}\) is squared in the balanced chemical equation.

So, the order of the reaction is: (3) 2