For the reaction, $\mathrm{NO}_{2(\mathrm{~g})}+\mathrm{CO}_{(\mathrm{g})} \longrightarrow \mathrm{NO}_{(\mathrm{g})}+\mathrm{CO}_{2(\mathrm{~g})}$, rate of formation of $\mathrm{NO}_{(\mathrm{g})}$ is $\mathrm{Y} \mathrm{mol} \mathrm{dm} \mathrm{ds}^{-1}$. Find the rate of disappearance of $\mathrm{CO}_{(\mathrm{g})}$.

Identify the compound formed by action of chromyl chloride on toluene in presence of $\mathrm{CS}_2$ and hydrolysed further?

Which from following compounds has lowest $\mathrm{pK}_{\mathrm{b}}$ value?