Assertion–Reason on Dipole Moment of NH₃ and NF₃

Statement – I:
Since Fluorine is more electronegative than nitrogen, the net dipole moment of NF₃ is greater than NH₃.

Statement – II:
In NH₃, the orbital dipole due to lone pair and the dipole moment of N–H bonds are in opposite direction, but in NF₃ the orbital dipole due to lone pair and dipole moments of N–F bonds are in same direction.

Choose the correct option.

Correct Answer: (C) Both Statement I and Statement II are false

Explanation

In NH₃, the dipole moments of N–H bonds and the lone pair dipole are in the same direction, therefore they add up, resulting in a higher net dipole moment.

In NF₃, although fluorine is more electronegative, the N–F bond dipoles are opposite to the lone pair dipole. Hence, they partially cancel each other.

As a result:

• Dipole moment of NH₃ is greater than NF₃
• Statement I is false
• Statement II is also false

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