Identify X, Y and Z in the following reactions :
(a) `C_(6)H_(5)NH_(2) underset(HCl)overset(NaNO_(2))rarr X underset(HBr)overset(CuBr)to Y underset("623 K, pressure")overset(NaOH)to Z`
(b) `C_(6)H_(6) overset(Cl_(2).FeCl_(3))to X overset(CuCN)to Y underset(H_(2)O)overset(dil.HCl)to Z`
(c) `C_(6)H_(5)N_(2)^(+)Cl^(-) underset("warm")overset(KI)to X overset(Cu)to Y`

Explanation

To identify X, Y, and Z in the given reactions, we will analyze each reaction step by step.

### Reaction (a):
1. **Starting Material**: Aniline (C₆H₅NH₂) reacts with HCl and NaNO₂.
- **Reaction**: Aniline undergoes diazotization in the presence of HCl and NaNO₂, forming diazonium chloride.
- **Product (X)**: C₆H₅N₂Cl (Benzene diazonium chloride).

2. **Next Step**: The diazonium salt (X) reacts with HBr and CuBr.
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