Question

Which one of the following statements is true?

• A. the dipole moment of $NF _{3}$ is zero
• B. the dipole moment of $NF _{3}$ is less then $NH _{3}$
• C. the dipole moment of $NF _{3}$ is more than $NH _{3}$
• D. the dipole moment of $NF _{3}$ is equal to $NH _{3}$

Answer 1

Answer: (B)

$NF _{3}$ 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 $0.234\, D )$. 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.