MHTCET 11 May 2024 Shift 2 Paper

Concept:The instantaneous rate of a reaction is expressed by dividing the rate of change of concentration of each species by its stoichiometric coefficient.Explanation:For a general reaction $a\mathrm{A} + b\mathrm{B} \longrightarrow c\mathrm{C} + d\mathrm{D}$, the instantaneous rate is written as:$$-\frac{1}{a}\frac{d[\mathrm{A}]}{dt} = -\frac{1}{b}\frac{d[\mathrm{B}]}{dt} = \frac{1}{c}\frac{d[\mathrm{C}]}{dt} = \frac{1}{d}\frac{d[\mathrm{D}]}{dt}$$Here, $a$, $b$, $c$, and $d$ are the stoichiometric coefficients of $\mathrm{A}$, $\mathrm{B}$, $\mathrm{C}$, and $\mathrm{D}$ respectively.The negative signs indicate the consumption of reactants $\mathrm{A}$ and $\mathrm{B}$, while the positive signs indicate the formation of products $\mathrm{C}$ and $\mathrm{D}$.Since the given expression matches exactly this form, the balanced reaction must include all four coefficients $a$, $b$, $c$, and $d$.Thus, the reaction is represented as $a\mathrm{A} + b\mathrm{B} \longrightarrow c\mathrm{C} + d\mathrm{D}$.Answer:The correct option is C: $a\mathrm{A} + b\mathrm{B} \longrightarrow c\mathrm{C} + d\mathrm{D}$.