Question

Which of the following is not an example of flexible groups?

• A. $-CH=C{H}_2$
• B. $-N=N-$
• C. Phenyl group
• D. $-CN$

Answer 1

The correct option is D $-CN$

Atoms/substituents attached to the conjugate system which show both +M as well as -M effect are known as flexible groups. Option (a), (b) and (c) are examples of flexible groups but $-CN$ group is an example of -R/-M group.