The decreasing order of acidic strength for following acids is
(a) `CH_3COOH` , (b)`CH_3CH ClCH_2COOH` , (c ) `ClCH_2COOH` , (d) `Cl_2CHCOOH`

Options

A. `B gt C gt A gt D`
B. `D gt C gt B gt A`
C. `D gt B gt C gt A`
D. `C gt D gt B gt A`

Answer

B

Explanation

Key Idea Acidic strength increases with presence of EWG (i.e. groups show -I effect) and decreases with the presence of EDG (i.e. groups show + I or hyperconjugation effect). More be the number and more close be the EWG to the `-COOH` group, more is the acidic strength.
(A) `overset(2)(C)H_(3)-overset(1)(C)OOH`, has only EDG, i.e., (by hyperconjugation) one `CH_(3)` group is bonded with `-COOH` group.
(B) `{:(CH_(3)-overset(3)(C)H-overset(2)(C)H_(2)-overset(1)(C)OOH),(" |"),(" Cl"):}`, has one EWG (i.e. Cl) at C-3 position and `CH_(3)`, i.e.one EDG (by hyperconjugation) at `C_(3)`-position.
(C) `Cl-overset(2)(C)H_(2)-overset(1)(C)OOH`, has one EWG (i.e., Cl-atoms) at `C_(2)-` position.
(D) `Cl_(2)-overset(2)(C)H-overset(1)(C)OOH`, has two EWG's (i.e. two Cl-atom) at `C_(2)`-position.
Thus, order of acidic strength is
`(D) gt (C) gt (B) gt (A)` and option (b) is the correct answer.