In which of the following pairs II is more stable than I

Options

A.
B. `CH_(3)-overset(o+)(C)=O and CH_(3)-C-=overset(o+)(O)`
C.
D. `CH_(3)-overset(o+)(C)H_(2)` & `CD_(3)-overset(o+)(C)H_(2)`

Answer

B, C

Explanation

(A).
`+H` is more dominating than I and can destabilised carbanion therefore Ist is more stable than II
(B). `CH_(3)-C-=overset(o+)(O)` Complete octet
(C). if `-Cl` and `-F` are obtained with conjugated system than overall electron with drawing effectof `-Cl` is more than that of `-F`
(D) `CH_(3)-overset(o+)(C)H_(2)` due to effective hyper conjugate.