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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3g2158

Which statements are correct? ( $p K_{a}$ : benzoic acid 4.20, salicylic acid 2.97, 4-hydroxybenzoic acid 4.58.)

ASalicylic acid is a stronger acid than benzoic acid.
B4-Hydroxybenzoic acid is a weaker acid than benzoic acid because the $+ M$ effect of $OH$ destabilises the carboxylate.
CIntramolecular hydrogen bonding in the salicylate ion explains its enhanced stability.
DThe phenolic $OH$ of the salicylate ion is more acidic than the phenolic $OH$ of the 4-hydroxybenzoate ion because of the same hydrogen bond.

Answer: A, B, C

A is true (2.97 against 4.20). B is true (4.58 against 4.20). C is true: the ortho

OH

H-bonds to the carboxylate and stabilises it. D is false: the same H-bond holds the phenolic proton in place and raises the second

p K_{a}

to about 13.6, making it harder, not easier, to ionise.

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