The product (P) formed from the following multistep reaction is:

Solution

Chemistry ma’am · 4 steps

The nitro group only steers the bromine; then H₃PO₂ wipes the nitrogen off the ring.

1. Where bromine goes. In p-nitrotoluene, CH₃ is an ortho/para director and NO₂ is a meta director. The para position of CH₃ is already taken, so both groups point to the same carbon: ortho to CH₃ and meta to NO₂. This gives 2-bromo-4-nitrotoluene.
2. Nitro to amine. H₂/Pd reduces -NO₂ to -NH₂, giving 2-bromo-4-methylaniline. Then NaNO₂ and HCl at 0 °C turn -NH₂ into the diazonium group -N₂⁺Cl⁻.

   Ar-N₂⁺Cl⁻ + H₃PO₂ + H₂O → Ar-H + N₂ + H₃PO₃ + HCl

3. Remove the nitrogen. Hypophosphorous acid replaces -N₂⁺ with H, not with OH. So the ring carbon that held the nitrogen ends up bare, and only CH₃ and Br remain, side by side.
4. So. P is 2-bromotoluene (o-bromotoluene), which is option (a).

The idea to keep. Use NO₂ to NH₂, then diazotisation and H₃PO₂, when a group is needed only to steer substitution. It sets the position, then leaves as N₂ with H in its place.

Answer from the NTA final answer key. Solution by PrepWiser.