Question

Bcl3 is a planar molecule whereas ncl3 is pyramidal because (a) nitrogen atom in smaller than boron atom (b) n – cl bond is moe covalent than b – cl bond (c) b – cl bond is more polar than n–cl bond (d) bcl3 has no lone pair of electrons where ncl3 has a lone pair of electrons.

Answer 1

d) bCl3 has no LP of electrons whereas NCl3 has 1 LP.....

Answer 2

Answer: (d) $BCl_3$ has no lone pair of electrons where $NCl_3$ has a lone pair of electrons.

Explanation: Formula used

$:{\text{Number of electrons}} =\frac{1}{2}[V+N-C+A]$

where, V = number of valence electrons present in central atom  

N = number of monovalent atoms bonded to central atom

C = charge of cation

A = charge of anion

1. $BCl_3$

${\text{Number of electrons}} =\frac{1}{2}[3+3-0+0]=3$

The number of electrons is 3 that means the hybridization will be $sp^2$ and the electronic geometry of the molecule will be trigonal planar. As there are three atoms around the central atom, the molecular geometry will also be trigonal planar.

2. $NCl_3$

${\text{Number of electrons}} =\frac{1}{2}[5+3-0+0]=4$

The number of electrons is 4 that means the hybridization will be $sp^3$ and the electronic geometry of the molecule will be tetrahedral but as there are three atoms around the central atom , the fourth position will be occupied by lone pair of electrons.