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Which of the following statements are correct?
(i) Inductive effect and resonance effect is possible in chlorobenzene.
(ii) Resonance effect dominates over inductive effect in anisole.
(iii) $p$-nitrobenzoic acid is less acidic than $m$-nitrobenzoic acid.
(iv) Diphenylamine is more basic than aniline.
Options:
(i) Inductive effect and resonance effect is possible in chlorobenzene.
(ii) Resonance effect dominates over inductive effect in anisole.
(iii) $p$-nitrobenzoic acid is less acidic than $m$-nitrobenzoic acid.
(iv) Diphenylamine is more basic than aniline.
Solution:
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Verified Answer
The correct answer is:
(i) and (ii)
(i) The $\mathrm{Cl}$ group activates benzene ring more by resonance effect.
$\mathrm{Cl}$ group being more electronegative withdraws electrons from benzene ring and shows - I effect.
(ii) The methyl group of ether can donate electrons through inductive effect that is not as strong as electron donation effect to the pi-system.
So, resonance effect dominates over inductive effect in anisole.
(iii) $p$-nitrobenzoic acid is more acidic than $m$-nitrobenzoic acid. When both acids donate $\mathrm{H}^{+}$ from $-\mathrm{COOH}$ group, then $p$-nitrobenzoate is more stabilised due to $m$-effect of nitro group at meta position by deactivating the ring.
So, statement (iii) is incorrect.
(iv) Diphenylamine is less basic than aniline. The lone pair of $\mathrm{N}$-atom in diphenylamine is delocalised on two benzene rings due to which it is less available to donate resulting into decrease in basicity. In aniline, it is delocalised on one benzene ring, so lone pair is more available for donation. Hence, it is more basic.
So, statement IV is incorrect.
$\mathrm{Cl}$ group being more electronegative withdraws electrons from benzene ring and shows - I effect.
(ii) The methyl group of ether can donate electrons through inductive effect that is not as strong as electron donation effect to the pi-system.
So, resonance effect dominates over inductive effect in anisole.
(iii) $p$-nitrobenzoic acid is more acidic than $m$-nitrobenzoic acid. When both acids donate $\mathrm{H}^{+}$ from $-\mathrm{COOH}$ group, then $p$-nitrobenzoate is more stabilised due to $m$-effect of nitro group at meta position by deactivating the ring.
So, statement (iii) is incorrect.
(iv) Diphenylamine is less basic than aniline. The lone pair of $\mathrm{N}$-atom in diphenylamine is delocalised on two benzene rings due to which it is less available to donate resulting into decrease in basicity. In aniline, it is delocalised on one benzene ring, so lone pair is more available for donation. Hence, it is more basic.
So, statement IV is incorrect.
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