Give the decreasing order of ease of decarboxylation of the following acids on heating with soda lime.
(a) (I) `CH_3 COOH`
(II)
(III) `Cl_3 C - COOH`.
(b) (I) `PhCOOH`
(II)
(III)
( c) (I) `Cl_3 C - COOH`
(II) `Br_3 C - COOH`
(III) `I_3 C-COOH`
(d) (I)

Explanation

(a) `(III) gt (II) gt (I)`
(b) `(II) gt (I) gt (III)`
Explanation :
(II)
(I)
(III)
( c) `(-I)` effect of `Cl gt Br gt I`. The decreasing order of stabilities of carbanion : `Cl_3 C^(Ӫ) gt Br_3 C^(Ӫ) gt I_3 C^(Ӫ)`.
Hence, the decreasing order of ease of decarboxylation : `(I) gt (II) gt (III)`
(d) `(III) gt (II) gt (I)`
`(III)` has three `EW (-NO_2)` groups `[(-I)` and `(-R)]`, `(II)` has two `EW(-NO_2)` groups and `(I)` has only one `EW(-NO_2)` group. The stability of carbanion and the ease of decarboxylation is `(III) gt (II) gt (I)`.