Question

Which of the following is an incorrect statement ?

• A. Hydrogen bonding is stronger than dispersion forces
• B. Sigma bonds are stronger than π-bonds
• C. Ionic bonding is non-directional
• D. σ-electrons are referred to as mobile electrons

Answer 1

The Correct Option is D

Let's evaluate each statement:

• Hydrogen bonding is stronger than dispersion forces: This is correct. Hydrogen bonds are stronger than dispersion forces, as hydrogen bonds involve strong electrostatic interactions between a hydrogen atom and highly electronegative atoms like oxygen, nitrogen, or fluorine.
• Sigma bonds are stronger than pi-bonds: This is correct. Sigma bonds, formed by head-on overlap of atomic orbitals, are stronger than pi-bonds, which are formed by side-by-side overlap.
• Ionic bonding is non-directional: This is correct. Ionic bonds are formed between oppositely charged ions, and the force of attraction is the same in all directions around the ion, making it non-directional.
• σ-electrons are referred to as mobile electrons: This is incorrect. π-electrons are referred to as mobile electrons in metals, not σ-electrons. π-electrons are free to move within the electron cloud, contributing to conductivity. σ-electrons are localized and involved in bonding.

Therefore, the incorrect statement is (D): σ-electrons are referred to as mobile electrons

Answer 2

1. Evaluate each statement:

- (A) Hydrogen bonding is stronger than dispersion forces: This is generally true. Hydrogen bonds are a type of dipole-dipole interaction and are stronger than London dispersion forces, which are present in all molecules.

- (B) Sigma bonds are stronger than π-bonds: This is true. Sigma bonds involve greater orbital overlap than pi bonds, resulting in stronger bonds.

- (C) Ionic bonding is non-directional: This is true. Ionic bonds result from electrostatic attraction between ions, which is non-directional and extends in all directions.

- (D) σ-electrons are referred to as mobile electrons: This is incorrect. Sigma electrons are localized between the bonded atoms and are not typically considered highly mobile. Pi electrons, particularly in conjugated systems, are more mobile than sigma electrons.

2. Conclusion
The incorrect statement is (D).

Final Answer:
(D) σ-electrons are referred to as mobile electrons