Compare the polarity nature of `NH_(3) and NF_(3)`.

Explanation

Both `NH_(3) and NF_(3)` have pyramidal sphaes with a long pair of electrons on nitrogen atom Fluorine is more electronegatvie than nitrogen. Dipole moment of N-II bond is less than that of N-f bond. Inspite of this the dipole moment of `NH_(3)(4.9xx10^(30) cm)` is greater than that of `NH(0.8xx10^(-30)` cm). This can be explained by observing the structure of `NH_(3) and NF_(3)`.

The dipole due to lone pair of electrons is acting in the same direction as the resultant dipole moment of N-H bonds. The two actions put together result in ammonia having higher dipole moment.

In `NF_(3)` the direction of orbital dipole moment due to lone pari is opposite to the direction of resultant dipole moment of `3N-F` bonds. The magnitudes of dipole moments are not same. As a result the net dipole omement of `NF_(3)` will decreases.