Question

[Assertion]:- All molecules with polar bond have non-zero dipole moments

[Reason]:- Dipole moment is a vector quantity

• A. if both assertion and reason are correct, and reason is the correct explanation of the assertion.
• B. If both assertion and reason are correct, but reason is not the correct explanation of the assertion.
• C. If assertion is correct, but reason is incorrect.
• D. If assertion is incorrect, but reason is correct.

Answer 1

The correct option is D If assertion is incorrect, but reason is correct.

Dipole moment is a vector quantity because it has both magnitude and direction.

The directionality of a polar covalent bond is due to the electro-negativity difference of the atoms involved in the bonding.

However, due to geometry and shape, the dipole moment vectors may cancel out leading to zero net dipole moment.

For instance, $CC{l}_4$ has very polar bonds but owing to the symmetrical geometry of the molecules, the vector sum of these 4 dipoles cancel out overall.