Question

For a reaction; $X+Y\to Z,rate\propto \left[X\right]$. What is (i) molecularity and (ii) order of the reaction?

• A. (i) $2$, (ii) $1$
• B. (i) $2$, (ii) $2$
• C. (i) $1$, (ii) $1$
• D. (i) $1$, (ii) $2$

Answer 1

The correct option is A (i) $2$, (ii) $1$

Molecularity is the number of molecules that come together to react in an elementary (single-step) reaction and is equal to the sum of stoichiometric coefficients of reactants in this elementary reaction.

Two molecules, $X$ and $Y$ are taking part in this reaction so the molecularity of the reaction is $2$.

Order of reaction is given by the rate law, power of $X$ is $1$ in the rate law, so the order of the reaction is $1$.

Hence, the correct answer is option $\text{A}$.