Question

Which of the following compounds do not exist?

$N_4,P_4,PC{I}_5,NC{I}_5,P_2{O}_5,N{O}_2,P{O}_2$ :

• A. $N_4,NC{I}_5,N{O}_2$
• B. $N_4,NC{I}_5,P{O}_2$
• C. $PC{I}_5,NC{I}_5,P{O}_2$
• D. All of these

Answer 1

The correct option is B $N_4,NC{I}_5,P{O}_2$

$NC{I}_5$ does not exist bcoz nitrogen atom does not have d-orbitals to accomodate electrons from chlorine atoms and nitrogen cant accomodate more than 8 electrons in its valence shell. so its covalency exists only upto four

$N-2s^2{p}^3$
$P-3s^2{p}^3$ but as P can expand its valency using vacant d-orbitals so maximum valency of N & P are 3 and 5.
So $N_4$ doesnt exist.

also, P doesnt form divalent compounds so $P{O}_2$ doesnt exist.