The hybridizations of atomic orbitals of nitrogen in ${\text{NO}}_2^{+}$, ${\text{NO}}_3^{-}$ and ${\text{NH}}_4^{+}$ respectively are:

1. ${\text{NO}}_2^{+}$: Nitronium ion. Steric number $=2+0=2$. Hybridization $=sp$ (Linear).2. ${\text{NO}}_3^{-}$: Nitrate ion. Steric number $=3+0=3$. Hybridization $=s{p}^2$ (Trigonal planar).3. ${\text{NH}}_4^{+}$: Ammonium ion. Steric number $=4+0=4$. Hybridization $=s{p}^3$ (Tetrahedral).