More practice questions

3. Q3. Write the equation for diazotising 4-methylaniline with NaNO₂ and HCl.

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   p-CH₃C₆H₄NH₂ + NaNO₂ + 2HCl → p-CH₃C₆H₄N₂⁺Cl⁻ + NaCl + 2H₂O, at 273–278 K (reasoned from NCERT page 274).

4. Q4. Give the formula of benzenediazonium hydrogensulphate and name its anion.

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   C₆H₅N₂⁺HSO₄⁻; the anion is hydrogensulphate, HSO₄⁻ (NCERT page 274).

5. Q5. Convert 273 K and 278 K to degrees Celsius.

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   Exactly, 273 − 273.15 = −0.15 °C and 278 − 273.15 = 4.85 °C. NCERT rounds this interval to approximately 0–5 °C (reasoned).

6. Q6. Why does an arenediazonium ion survive at 273–278 K while an alkyldiazonium ion does not? (Compare NCERT Exercise 9.3 (vi), page 278.)

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   The arenediazonium ion is stabilised by resonance with the benzene ring; an alkyldiazonium ion has no such stabilisation and loses nitrogen at once (NCERT page 274; reasoned).