(∵NO2 is m -directing group while CH3 group is O− and p - directing group. Thus, Br group attach at o -position with respect to CH3 and m -position with respect to NO2 group) Step 2. On reductionwith Sn∕HCl,NO2− group changes to −NH2 group.
Step 3. On treatment with NaNO2+HCl;NH2 changes to diazo group (i.e. Q shows diazotisation).
Step 4. On treatment with H3PO2, only diazo group (N2Cl) reacts and gets removed
Step 5. On oxidation with KMnO4∕OH−−CH3 group changes to- COOHgroup.