(a) write the products formed when `CH_(3)CHO` reacts with the following reaction:
(i) HCN
(ii) `H_(2)N-OH`
(iii) `CH_(3)CHO` in the presence of dilute NaOH
(b) Give simple chemical test to distinguish between the following pairs of compound
(i) Benzoic acid and phenol
(ii) Propanal and propanone

Explanation

### Step-by-Step Solution

#### Part (a): Products formed when `CH₃CHO` reacts with the following reagents:

1. **Reaction with HCN (Hydrogen Cyanide)**:
- When acetaldehyde (`CH₃CHO`) reacts with hydrogen cyanide (`HCN`), it forms a cyanohydrin.
- The reaction can be represented as:
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