Question

The electronegativity difference between $N$ and $F$ is greater than that between $N$ and $H_4$ yet the dipole moment of $NH_3$ (1.5 D) is larger than that of $NF_3$ (0.2 D). This is because :-

• A. in $NH_3$ as well as in $NF_3$, the atomic dipole and bond dipole are in the same direction
• B. in $NH_3$, the atomic dipole and bond dipole are in the same direction whereas in $NF_3$ these are in opposite directions
• C. in $NH_3$ as well as $NF_3$, the atomic dipole and bond dipole are in opposite directions
• D. in $NH_3$ the atomic dipole and bond dipole are in the opposite directions whereas in $NF_3$ these are in the same directions

Answer 1

Answer: (B)

Electronegativity of N is greater than that of H, but in $NF_3$ electronegativity of F is greater than that of N. So, in $NH_3$ the atomic dipole and bond dipole are in the same direction whereas in $NF_3$ these are in opposite direction.