Question

Which nitrogen trihalide is least basic?

• A. $N{F}_3$
• B. $NC{l}_3$
• C. $NB{r}_3$
• D. $N{I}_3$

Answer 1

Answer: (A)

$N{F}_3$

The basicity increases down the group because the electronegativity decreases down the group. Base need to be able to donate electrons. Fluorine being the most electronegative draws the electron density towards it and thus it is difficult for nitrogen atom to donate the lone pair of electron. Down the group as electronegativity decreases the basicity increases.

Hence option A is correct.