Question

Which of the following statements are true with respect to electronic displacement in a covalent bond?
I. Inductive effect operates through $\pi$-bond.
II. Resonance effect operates through $\sigma$-bond.
III. Inductive effect operates through $\sigma$-bond.
IV. Resonance effect operates through $\pi$-bond.
V. Resonance and inductive effects operate through $\sigma$-bond.

• A. III and IV
• B. I and II
• C. II and IV
• D. I and V

Answer 1

The correct option is A III and IV

The statements III and IV are true with respect to electronic displacement in a covalent bond.
III. Inductive effect operates through $\sigma -$ bond.
Inductive effect is permanent but weak effect involving displacement of $\sigma -$ electrons towards more electronegative species.
It can be transmitted through a chain of C atoms.

IV. Resonance effect operates through $\pi -$ bond.

The following example illustrates resonance.

$C{H}_2=CH-CH=C{H}_2\leftrightarrow C{H}_2^{+}-CH=CH-C{H}_2^{-}\leftrightarrow C{H}_2^{-}-CH=CH-C{H}_2^{+}$