Question

The electronegativity difference between N and F is greater than that between N and H yet the dipole moment of NH3 (1.5 D) is larger than that of NF3 (0.2 D). This is because:

• A. in NH3 as well as in NF3 the atomic dipole and bond dipole are in the same direction
• B. in NH3 the atomic dipole and bond dipole are in the same direction whereas in NF3 these are in opposite directions
• C. in NH3 as well as NF3 the atomic dipole and bond dipole are in opposite directions
• D. in NH3 the atomic dipole and bond dipole are in the opposite directions whereas in NF3 these are in the same directions

Answer 1

Answer: (B)

in NH3 the atomic dipole and bond dipole are in the same direction whereas in NF3 these are in opposite directions

Answer 2

Despite the fact that the electronegativity difference between nitrogen (N) and fluorine (F) is larger than that between nitrogen (N) and hydrogen (H), the dipole moment of NH3 (1.5 D) exceeds that of NF3 (0.2 D). This discrepancy arises because in NH3, the atomic dipole moments and bond dipole moments align in the same direction, while in NF3, they are oriented in opposite directions.

So, the correct option is (B): in NH3 the atomic dipole and bond dipole are in the same direction whereas in NF3 these are in opposite directions.