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Assertion: The pK(a) of acetic acid is l...

Assertion: The `pK_(a)` of acetic acid is lower than that of phenol.
Reason : Phenoxide ion is more resonance sabilised.

A

If both assertion and reason are true and the reason is the correct explanation of the assertion.

B

If both assertion and reason are true but reason is not the correct explanation of the assertion.

C

If assertion is true but reason is false.

D

If the assertion and reason both are false.

Text Solution

Verified by Experts

The correct Answer is:
C
Acetic acid is stronger acid than phenol so its `pK_(a)` value is lower than that of phenol. Thus assertion is true.
In phenoxide ion the negative charge is delocalized in one H atom and three C atoms but in ethanoate ion the negative charge is delocalized in two oxygen atoms. As oxygen is more electronegative than carbon atom so the resonance stability will be more in the case of ethanoate ion and ethanoic acid is more acidic than phenol.
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