Explanation

(d)
$2SO_{2}(g) + O_{2}(g) \rightleftharpoons 2SO_{3}(g)$
For this reaction, rate
${(r}_{1}) = k\left\lbrack SO_{2} \right\rbrack_{1}^{2}\left\lbrack O_{2} \right\rbrack_{1}\ \ \ \ \ \ \ \ \ \ldots.(i)$
On doubling the volume of vessel, concentration would be half. Hence,
Rate$\left( r_{2} \right) = k\left( \frac{\left\lbrack SO_{2} \right\rbrack_{1}}{2} \right)^{2}\left( \frac{\left\lbrack O_{2} \right\rbrack_{1}}{2} \right) = \frac{r_{1}}{8}$
$\frac{r_{1}}{r_{2}} = 8:1$