Question

Polar molecules are the molecules:

• A. having zero dipole moment
• B. acquire a dipole moment only in the presence of electric field due to displacement of charges
• C. acquire a dipole moment only when magnetic field is absent
• D. having a permanent electric dipole moment

Answer 1

The Correct Option is D

To determine which option correctly describes polar molecules, we need to understand the key concept of molecular polarity.

Concept of Polar Molecules: A molecule is said to be polar if it has a permanent electric dipole moment. This occurs when there is an uneven distribution of electron density across the molecule. Generally, polar molecules have regions of positive and negative charge, which results in the molecule having a dipole moment.

Analysis of the given options:

• Option 1: Having zero dipole moment - Molecules having zero dipole moment are non-polar, as they show a symmetric distribution of charge, leading to no overall dipole moment.
• Option 2: Acquire a dipole moment only in the presence of an electric field due to displacement of charges - This describes induced dipole moment situations, where a non-polar molecule can acquire a temporary dipole under an external electric field, but not a permanent one.
• Option 3: Acquire a dipole moment only when the magnetic field is absent - This option doesn't correctly relate to the concept of permanent dipole moments; also, magnetic fields do not induce or suppress electric dipoles.
• Option 4: Having a permanent electric dipole moment - This correctly describes polar molecules. A permanent dipole moment occurs due to the intrinsic asymmetry in the charge distribution within the molecule.

Conclusion: The correct answer is the option that describes polar molecules as having a permanent electric dipole moment, which is Option 4.