The `BCl_3` is a planar molecule whereas `NCl_3` is pyramidal because

Options

A. B-Cl bond is more polar than N - Cl bond
B. N-Cl bond is more covalent than B- Cl bond
C. nitrogen atom is smaller than boron atoms
D. `BCl_(3)` has no lone pair but `NCl_(3)` has a lone pair of electrons.

Answer

D

Explanation

(Central B atom)
No lone pair of electrons is svailable in `BCl_(3)`.

(Central N atom)
One lone pair of electrons is available on N atom, it occupies a corner in the tetrahedral arrangement.
Therefore, `NCl_(3)` appears pyramidal in shape.