Question

Arrange these compounds in their decreasing order of acidic strength.

• A. P > R > Q > S
• B. S > R > Q > P
• C. P > S > Q > R
• D. Q > S > P > R

Answer 1

The correct option is A P > R > Q > S

o-Methylbenzoic Acid (P) is the most acidic compound among the all given compounds because of both +I and +H effect.

Also p-Methylbenzoic acid (R) due to +H effect is more acidic than m-Methylbenzoic acid (Q) due to +I effect because +H effect is more electron donating effect than +I effect.

Whereas, benzoic acid with no electron donating group is the least acidic compound among the given ones.

So, the order of acidic strength is $P>R>Q>S$

Hence, Option "A" is the correct answer.