Consider of following reactions
`CHF_(3) overset(K_(a))(to)CF_(3)^(-)+H^(+)`
`CHCl_(3)^(-) overset(K_(a)^(+))(to)C Cl_(3)^(-)+H^(+)`
Then regarding given reactions which of the following statement(s) is /are correct:

Options

A. `K_(a)gtK'_(a)`
B. `CHF_(3)` act as a stronger bronsted acid than `CHCl_(3)`
C. `C Cl_(3)^(-)` is more stable than `CF_(3)^(-)`
D. `C Cl_(3)^(-)` is weaker lewis base than `CF_(3)^(-)`

Answer

C, D

Explanation

`K._(a)gtK_(a)`
`CHF_(3)overset(K_(a)) to CF_(3)^(-)+H^(+)`
stabilized by inductive effect of F-atoms
`CHCl_(3)overset(K._(a))CCl_(3)^(-)+H^(+)`
Due to combined effect in inductive effect of Cl-atom and `2p_(pi)-3d_(pi)` back bonding, lone pair at C-atom (negative charge) in `CCl_(4)^(-)` is more delocalized than in `CF_(3)^(-)` is more stable than `CF_(3)^(-) and CCl_(3)^(-)` is weaker lewis base than `CF_(3)^(-)`