For a certain reaction, the rate $=k[A{]}^2[B]$. When the initial concentration of $A$ is tripled keeping the concentration of $B$ constant, the initial rate would

Solution & Explanation

\textbf{Answer:} (C) Increase by a factor of nine \textbf{Solution:} Given rate law $R=k[A{]}^2[B]$. Tripling $[A]$ with $[B]$ constant: $R^{\prime }=k(3[A]{)}^2[B]=9k[A{]}^2[B]=9R$. Therefore $\frac{R^{\prime }}{R}=9$, i.e. the rate increases by a factor of nine.