Question

The molecule having zero dipole moment is

• A. BF₃
• B. HF
• C. NH₃
• D. CH₃CI

Answer 1

The Correct Option is A

The question asks which of the given molecules has a zero dipole moment. To determine this, we need to understand the concept of molecular geometry and dipole moments:

A dipole moment is a measure of the separation of positive and negative charges in a molecule. The dipole moment depends on the difference in electronegativity between atoms and the geometry of the molecule.

1. BF₃ (Boron Trifluoride): BF₃ is a non-polar molecule. It has a trigonal planar structure where three fluorine atoms are symmetrically arranged around the boron atom at 120-degree angles. The symmetrical arrangement results in the cancellation of dipole moments, leading to a net dipole moment of zero.
2. HF (Hydrogen Fluoride): HF is a polar molecule because it consists of hydrogen and fluorine atoms with a significant difference in electronegativity, resulting in a dipole moment along the H-F bond.
3. NH₃ (Ammonia): NH₃ is a polar molecule with a trigonal pyramidal shape. Its dipole moment is not zero because the lone pair of electrons on nitrogen results in a net dipole moment.
4. CH₃Cl (Methyl Chloride): CH₃Cl is a polar molecule. The difference in electronegativity between carbon and chlorine induces a dipole moment along the C-Cl bond, making the overall molecule polar.

Based on the above analysis, the molecule with a zero dipole moment is BF₃, as its symmetrical trigonal planar shape results in the cancellation of individual bond dipoles.