The azide ions have. (A) 20 out electrons and this isoelectronic with B{r_2} O(B) 18 outer electrons and its isoelectronic with a N{O_2} (C) 16 outer electrons are in isoelectronic with C{O_2} (D) 14 outer electrons and is isoelectronic with {H_2} {O_2}

The correct option is (C) 16 outer electrons are in isoelectronic with CO2 (carbon dioxide).

Let's break down each option:

(A) Azide ions (N3-) have 20 outer electrons. This is not isoelectronic with Br2O, which has 18 outer electrons.

(B) Azide ions (N3-) have 18 outer electrons, not 18 as mentioned in this option. And they are not isoelectronic with NO2, which also has 18 outer electrons.

(C) Azide ions (N3-) have 16 outer electrons. This is indeed isoelectronic with CO2 (carbon dioxide), which also has 16 outer electrons.

(D) Azide ions (N3-) have 14 outer electrons, which is not isoelectronic with H2O2 (hydrogen peroxide), which has 18 outer electrons.

So, option (C) is the correct one. Azide ions (N3-) have 16 outer electrons and are isoelectronic with CO2.