Starting from benzene or toluene or aniline and with the aid of diazonim salt synthesis the following :
a. p-Nitrobenzene
b. p-Cyano benzoic acid

Explanation

To synthesize p-Nitrobenzene and p-Cyano benzoic acid starting from aniline and toluene respectively, we can follow these steps:

### Synthesis of p-Nitrobenzene from Aniline:

1. **Formation of Diazonium Salt:**
- Start with **aniline (C6H5NH2)**.
- Treat aniline with **nitrous acid (HNO2)**, which can be generated in situ from sodium nitrite (NaNO2) and hydrochloric acid (HCl).
- This reaction will produce **benzenediazonium chloride (C6H5N2+ Cl-)**.
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