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

The Correct Option is B

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.