(a) Write the structures of main products when benzene diazonium chloride reacts with the following reagents :
(i) `H_(3)PO_(2)+H_(2)O`
(ii) `CuCN//KCN`
(iii) `H_(2)O`
(b) Arrange the following in the increasing order of their basic character in an aqueous solution :
`C_(2)H_(5)NH_(2),(C_(2)H_(5))_(2)NH,(C_(2)H_(5))_(3)N`
(c) Give a simple chemical test to distinguish between the following pair of compounds :
`C_(6)H_(5)-NH_(2) and C_(6)H_(5)-NH-CH_(3)`

Explanation

### Step-by-Step Solution

#### (a) Structures of Main Products from Benzene Diazonium Chloride Reactions

1. **Reaction with `H3PO2 + H2O`:**
- Benzene diazonium chloride (C6H5-N2^+Cl^-) reacts with phosphorous acid (H3PO2) and water (H2O).
- The nitrogen gas (N2) is released, and the main product formed is benzene (C6H6).
- **Structure:**
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