NEET 2026 Chemistry Diazotisation MCQ Question

Topic: Reaction Mechanism → Diazotisation Difficulty: 🔴 Hard

✅ Ans: C → $C_2H_5OH$

Follow the sequence:

$$C_2H_6 \xrightarrow{Cl_2/h u} C_2H_5Cl$$ $$C_2H_5Cl\xrightarrow{NH_3} C_2H_5NH_2$$

Primary aliphatic amine + $NaNO_2/HCl$:

$$C_2H_5NH_2\xrightarrow{NaNO_2/HCl} C_2H_5N_2^+Cl^-$$

On hydrolysis:

$$C_2H_5N_2^+Cl^- \xrightarrow{H_2O} \boxed{C_2H_5OH}$$

❌ Other options

• A: $C_2H_5NO_2$ ❌ → nitro compound is not formed.
• B: $C_2H_5-N=N-OH$ ❌ → diazonium intermediate is unstable for aliphatic amines.
• D: $C_2H_5NH_2$ ❌ → this is intermediate Y, not final product.

📌 NCERT: Aliphatic primary amines form alcohols with evolution of nitrogen gas when treated with nitrous acid.

🧠 NEET Trick:

$$\boxed{1^\circ\text{ aliphatic amine}+HNO_2\rightarrow ROH+N_2\uparrow}$$