Which of the following option is incorrect regarding ${\mathrm{N}}_3^{-}$?

 Azide ion ${\mathrm{N}}_3^{-}$ has a linear structure and has 22 electrons

$\stackrel{\mathrm{\Theta }}{N}=\stackrel{\oplus }{N}=\stackrel{\mathrm{\Theta }}{N}$ No $p\pi -d\pi$ linkage 

The central $\mathrm{N}$atom in azide ion contains two bonding domains and zero lone pairs of electrons.

Hence, the correct option is C.