Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R: In the light of the above statements, choose the correct answer from the options given below:
- A is false but R is true.
- Both A and R are true but R is NOT the correct explanation of A.
- Both A and R are true and R is the correct explanation of A.
- A is true but R is false.
Answer
(4) A is true but R is false.
Solution
A: pKa of phenol = 10.0, of ethanol = 15.9 (NCERT values) ⇒ A is true
Lower pKa ⇒ stronger acid ⇒ phenol is the stronger acid
∵ Phenoxide ion is resonance-stabilised (charge delocalised into the ring); ethoxide is destabilised by +I of C2H5
⇒ R (ethanol stronger than phenol) is false
Answer: (4)