$\mathrm{NO}_2$ required for a reaction is produced by the decomposition of $\mathrm{N}_2 \mathrm{O}_5$ in $\mathrm{CCl}_4$ as per the equation, $2 \mathrm{~N}_2 \mathrm{O}_5(\mathrm{~g})$
$$
\rightarrow 4 \mathrm{NO}_2(\mathrm{~g})+\mathrm{O}_2(\mathrm{~g}) .
$$
The initial concentration of $\mathrm{N}_2 \mathrm{O}_5$ is $3.00 \mathrm{~mol} \mathrm{~L}^{-1}$ and it is $2.75 \mathrm{~mol} \mathrm{~L}^{-1}$ after 30 minutes.
The rate of formation of $\mathrm{NO}_2$ is