Question: Which of the following molecules has highest dipole moment?...

Question

Which of the following molecules has highest dipole moment?

Answer 1

Solution

Molecules with symmetrical geometries (like BF3 and B2H6) have zero net dipole moment due to the cancellation of individual bond dipoles. In pyramidal molecules like NH3 and NF3, the geometry is not symmetrical, and the lone pair contributes to the dipole moment. NH3 has a higher dipole moment than NF3 because the electronegativity difference between N and H is smaller than between N and F. In NH3, the bond dipoles and the lone pair dipole reinforce each other, while in NF3, the strong bond dipoles pointing towards fluorine oppose the lone pair's contribution more significantly.