Question

The molecule which has zero dipole moment is___?

• A. ${\mathrm{BF}}_3$
• B. ${\mathrm{NF}}_3$
• C. ${\mathrm{ClO}}_2$
• D. ${\mathrm{CH}}_2{\mathrm{Cl}}_2$

Answer 1

The correct option is A

${\mathrm{BF}}_3$

Explanation for correct option

(A)${\mathrm{BF}}_3$

Dipole moment

• The dipole moment can be defined as the product of the magnitude of the charge and the distance between the centers of positive and negative charges.
• If opposite charges (q) are separated by distance r, then dipole moment is expressed as
• $\mu =qxr$
• ${\mathrm{BF}}_3$has zero dipole moment because of its symmetrical molecular structure.

Explanation for incorrect options

• ${\mathrm{NF}}_3$ (Nitrogen trifluoride) has a lone pair of electrons on nitrogen atom hence dipole moment is not zero.

• ${\mathrm{ClO}}_2$(Chlorine dichloride) has a central chlorine atom bonded to two oxygen atoms. The dipole moment of the molecule is non-zero because there are two bond pairs and one lone pair on the central atom.

• ${\mathrm{CH}}_2{\mathrm{Cl}}_2$ (Dichloro-methane) is a polar molecule due to its tetrahedral geometrical shape and difference between the electronegativity of Carbon, Hydrogen, and Chlorine atoms. This develops a dipole moment in the molecule.
• Hence, options (B) , (C), and (D) are incorrect.

Hence, option (A) is correct. ${\mathrm{BF}}_3$ has zero dipole moment.