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.

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

Hint:

Inductive effect is a \(\sigma\)-bond phenomenon, while resonance (mesomeric) effect is a \(\pi\)-bond phenomenon.

Answer 1

The Correct Option is A

To determine which statements are true with respect to electronic displacement in a covalent bond, we need to understand the difference between the inductive effect and the resonance effect:

• Inductive Effect: This is a transmission of charge through a chain of atoms in a molecule by electrostatic induction. It typically operates through the \(\sigma\)-bond, altering the electron density along the chain.
• Resonance Effect: This involves the delocalization of electrons across adjacent atoms, particularly occurring through \(\pi\)-bonds. Resonance results in the stabilization of a molecule or ion.

Now, let's analyze the given statements:

1. Inductive effect operates through \(\pi\)-bond: This statement is false. The inductive effect operates through \(\sigma\)-bonds, not \(\pi\)-bonds.
2. Resonance effect operates through \(\sigma\)-bond: This statement is false. The resonance effect primarily operates through \(\pi\)-bonds due to electron delocalization.
3. Inductive effect operates through \(\sigma\)-bond: This statement is true. The inductive effect indeed operates through the \(\sigma\)-bonds, transmitting the influence of groups inductively.
4. Resonance effect operates through \(\pi\)-bond: This statement is true. The resonance effect operates through \(\pi\)-bonds, allowing for the delocalization of electrons across multiple bonds.

Based on the analysis, the correct answer is the option 'III and IV', as these statements accurately describe the operation of inductive and resonance effects in covalent bonds.