`BF_(3) and NF_(3)` both molecules, are covalent, but `BF_(3)` is non - polar and `NF_(3)` is polar.Its reason is

Options

A. boron is a metal and nitrogen is a gas in uncombined state.
B. `BF_3`bonds no dipole moment whereas `NF_3` bond have dipole moment.
C. atomic size of boron is smaller than that of nitrogen
D. `BF_3` is symmetrical molecule whereas `NF_3` is unsymmetrical.

Answer

D

Explanation

`BF_3` is symmetrical planar, although it has polar bonds but resultant dipole moment is zero. In `NF_3`, lone pair cause distortion, hence polarity arises.