Question

The dipole moment of $N{F}_3$ is less than that of $N{H}_3$ because:

• A. $N{H}_3$ forms associated molecules
• B. $F$ is more electronegative than $N$
• C. the resultant bond polarity is less
• D. the resultant of individual polarities is opposed by the polarity of lone pair in $N{F}_3$

Answer 1

Answer: (B), (D)

The correct options are
B $F$ is more electronegative than $N$
D the resultant of individual polarities is opposed by the polarity of lone pair in $N{F}_3$

Electronegativity of $F$ is more than $N$. $\therefore$ each of the $N-F$ bonds has its polarity towards $F$, which results in a net polarity which opposes the polarity of lone pair electrons. This is opposite to the case of $N{H}_3$.