Question

In which of the following molecules octet rule is not followed?

• A. $N{H}_3$
• B. $C{H}_4$
• C. $C{O}_2$
• D. $NO$

Answer 1

The correct option is D $NO$

Octet rule = Elements which have $1-7$ electrons in the outer most shell take part in the process of bond formation and acquire the nearest noble gas electronic configuration.

Here as shown in the image $N$ atom has one odd electron that is shown in red color forms bond with the two electrons of the oxygen atom. Hence total electrons that take part in bond formation are $7$ but as the octet rule electrons must be $8$ and in this way, octet rule is violated by $NO$ molecule. The nature to form dimer is also reduced due to this odd electron bond.