IIT JEE 2009 P1 Q8

well bhaiyaa i think that its C because the anion formed after deprotonation is most stable in C!
IV should be the least acidic and most basic as it shows +I to it!!!!!

cheers!!!!!!!!

well, even i got a !

answer is a dam sure

but CH₃ willl show +I effect and hence wil reduce acidity whereas Cl and OH will show -I effect and will increase acidity therefore answer must be (c)
plzz explain

@ jesh ... see the 4th compound has an cooh group .. its an acid ..it is going to be more acidic than chloro phenol

We decide by inductive effect here...using resonance is pretty much futile as OH is anyway +R and COOH is -R...doesn't help our cause. Had there been substrates where in one resonance is present and not in the other comparison would've worked that way.

Using inductive effect is much quicker. Benzoic acids are obviously more acidic than phenols. Let's decide phenols first. Chlorine exerts a huge -I effect which engulfs its tiny +R effect, so like I said we use inductive here. So chlorophenol is more acidic than phenol.
In the benzoic acids, methyl group provides +I effect which diminishes the acidity of the acid to some extent. So II > I and IV < III
The overall order becomes III > IV > II > I which is (A).

yes the answer is a.
as well explained by pritish.