Question

Which of the following has maximum dipole moment?

• A. $NC{l}_3$
• B. $NB{r}_3$
• C. $N{H}_3$
• D. $N{I}_3$

Answer 1

Answer: (C)

Electronegativity difference between $N(3.0)$ and $Cl(3.0)$ is zero and hence $N-Cl$ bonds are non-polar. As a result, the overall dipole moment of $NC{l}_3$ molecule and its direction is just the dipole moment of the lone pair of electrons.
On the other hand, $N-Br(3.0-2.8),$ $N-I(3.0-2.5)$ and $N-H(3.0-2.1)$ are polar and hence contribute towards the overall dipole moment of the respective molecules. Since the EN difference is highest in case of $N-H$ bonds, therefore, $N{H}_3$ has the highest dipole moment.