Question

Which one of the following statements is true?

• A. the dipole moment of $N{F}_3$ is zero
• B. the dipole moment of $N{F}_3$ is less then $N{H}_3$
• C. the dipole moment of $N{F}_3$ is more than $N{H}_3$
• D. the dipole moment of $N{F}_3$ is equal to $N{H}_3$

Answer 1

Answer: (B)

$N{F}_3$ has a pyramidal shape with one lone pair on $N$-atom.

The lone pair on $N$ is nin opposite direction to the $N-F$ bond moments and therefore, it has very low dipole moment (about $0.234D)$. Thus, it does not show dononr properties. But ammonia has high dipole moment because its lone pair is in the same direction as the $N-H$ bond moments, Thus it has dononr properties.