Step 1: Classification of Phenols Based on Hydroxyl Groups - Monohydric Phenol: Contains one \(-OH\) group (e.g., Phenol).
- Dihydric Phenol: Contains two \(-OH\) groups (e.g., Catechol).
- Trihydric Phenol: Contains three \(-OH\) groups (e.g., Pyrogallol).
Step 2: Structural Formulas

(i) Benzene from benzoic acid:
(ii) Phthalimide from phthalic acid:
(iii) \( m \)-Nitrobenzaldehyde from benzaldehyde:
(iv) Benzaldehyde from benzene:
(v) Silver mirror from \( C_6H_5CHO \):