MHTCET 11 Apr 2026 Shift 2 Paper

Concept:The order of a reaction is determined by the sum of the exponents of the concentration terms in the experimentally determined rate law.Explanation:The given reaction is:$$2 \mathrm{H}_{2}\mathrm{O}_{2}(l) \rightarrow 2 \mathrm{H}_{2}\mathrm{O}(l) + \mathrm{O}_{2}(g)$$However, the rate law is provided separately:$$\text{rate} = k\left[\mathrm{H}_{2}\mathrm{O}_{2}\right]$$In this rate law, the only concentration term is $\left[\mathrm{H}_{2}\mathrm{O}_{2}\right]$.Its exponent is $1$ (since it is raised to the power $1$).The order of the reaction is the sum of all exponents in the rate law, which is simply $1$.Therefore, the reaction is first order with respect to $\mathrm{H}_{2}\mathrm{O}_{2}$ and first order overall.Answer:The order of the reaction is $1$.Hence, the correct option is B. 1.