The strongest acid amongst the following compound is

Options

A. HCOOH
B. `CH_(3)CH_(2)CH(Cl)CO_(2)H`
C. `ClCH_(2)CH_(2)CH_(2)CO OH`
D. `CH_(3)CO OH`

Answer

2

Explanation

Electron releasing groups (Alkyl groups) de stabilizes conjugates base.
The +I effect of `CH_(3)` is less than -I effect of Cl `K_(a)` of HCOOH is `17.9xx10^(-5)`
`K_(a)` of `CH_(3)CH_(2)underset(Cl)underset(|)(C)H-CO OH` is `139xx10^(-5)`