Question

Which of the following halide is unstable?

• A. $N{F}_3$
• B. $PC{l}_3$
• C. $NC{l}_3$
• D. Both (a) and (c)

Answer 1

The correct option is C $NC{l}_3$

All the trihalides of grouyp $15$ elements are stable except $N{X}_3$. Only $N{F}_3$ is stable​ among all the​ halides of nitrogen.
The reason for the unstability of other trihalides are the bigger size of halogen atom as compared to nitrogen atom. Due to larger size difference in N and halogen the $N-X$ bond becomes weaker hence compound become unstable.
​Hence, option (c) is the correct answer.