Question

why nitrogen tri iodide is so unstable

Answer 1

Answer:

As the atomic radius of nitrogen is small when compared to iodine,

The iodine atoms are clustered together(each with a partial negative charge)

These atoms repel each other, making nitrogen tri iodide explosively unstable.

Answer 2

Answer:

$\huge\bold\purple{HELLO !!}$

These iodine atoms lie in close proximity to each other and cluster around one side of a nitrogen atom. Since they repel each other in small space, it causes bond strain, making the molecule explosively unstable.