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Given below are two statements : 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 NH bonds are in opposite direction, but in NF3 the orbital dipole due to lone pair and the dipole moments of N-F bonds are in same direction. In the light of the above statements, choose the most appropriate from the options given below :

1. Both Statement I and Statement II are true
2. Both Statement I and Statement II are false
3. Statement I is false but Statement II is true
4. Statement I is true but Statement II is false

Correct answer: Statement I is false but Statement II is true

Solution

Statement I is incorrect because, despite fluorine's higher electronegativity, the net dipole moment of NF3 is actually less than that of NH3 due to the geometry of the molecules. Statement II is correct as the lone pair in NH3 creates a dipole that opposes the N-H bonds, while in NF3, the dipoles from the N-F bonds align with the lone pair, resulting in a net dipole moment.

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