Which of the following carbocations is expected to be most stable?

Options

A.
B.
C.
D.

Answer

A

Explanation

`-NO_(2)` group is an electron withdrawing group and exhibit -I effect. This effect increases with decrease in distance of positive charge present on C-atom and hence lesser is the stability of carbocation.
In option (a), the positive charge is at maximum distance to `NO_(2)` group, so -I effect due to `NO_(2)` group will be minimum and stability will be maximum.

In option (b) and (d) the positive charges is at minimum distance to `NO_(2)` group hence the stability will be minimum.

Also, in option (c ) the distance of positive charge to `NO_(2)` group is more than ortho but less than para, so it will be less stable as compared to option (a).