# Which of the following compound CANNOT act as a Lewis base?

Question:

Which of the following compound CANNOT act as a Lewis base?

1. $\mathrm{NF}_{3}$

2. $\mathrm{PCl}_{5}$

3. $\mathrm{SF}_{4}$

4. $\mathrm{ClF}_{3}$

Correct Option: , 2

Solution:

Lewis base : Chemical species which has

capability to donate electron

pair.

In $\mathrm{NF}_{3}, \mathrm{SF}_{4}, \mathrm{ClF}_{3}$ central atom (i.e. $\mathrm{N}, \mathrm{S}, \mathrm{Cl}$ ) having lone pair therefore act as lewis base.

In $\mathrm{PCl}_{5}$ central atom $(\mathrm{P})$ does not have lone pair therefore does not act as lewis base.