Question

In which of following molecules, $\pi$ - electron density in ring is minimum?

• A.
• B.
• C.
• D.

Answer 1

The correct option is D

$N{O}_2$ group produces $-M$ effect, i.e., electron density decreases in the ring. $-OC{H}_3$ and $-N{H}_2$ groups produces $+M$ effect, i.e., electron density increases in the ring.
In option D, two $N{O}_2$ groups are present. At meta position it will produce $-I$ effect which will also lead to decrease in electron density of the ring.