. The electronegativity difference between N and F is greater


than that between N and H yet the dipole moment of NH(1.5D) is larger than that of NF3 (0.2D). This is because

 

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

(b) in NH3 as well as in NF3 the atomic dipole and bond dipole are in the same direction

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

(d) in NH3 as well as in NF3 the atomic dipole and bond dipole are in opposite directions.

Best Answer

Correct Option is: C

In NH3 the dipole is in same direction because of which it has more dipole moment than NF3. The difference is due to fact that the dipole moment due to N - F bonds in NF3 are in opposite directions to the direction of the dipole moment of the lone pair on N atoms which partly cancel out. The dipole moment of N - H bonds in NH3 are in the same direction of the dipole moment of the lone pair on N atom which adds up as shown:

atomic dipole and bond dipole

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