The statement true for `N_(3)^(-)` is

Options

A. it has a nonlinear structure
B. it is called a pseudohalogen
C. the formal oxidation state of nitrogen in this anion is `-1`
D. it is isoelectronic with `NO_2`

Answer

B, C

Explanation

The azide ion `(N_3^(-))` has 16 valence electrons and is isoelectronic with `CO_2`. The `N_3^(-)` ion is linear `(N-N-N)` like `CO_2` molecule. The formal oxidation state of nitrogen in this anion is `-1`, because the net charge on the ion is `-1` as shown in the following resonating structures.
`:overset(2-)overset(..)underset(..)N-overset(+)N-=overset(..)Nharroverset(..)N-=overset(+)N-overset(2-)overset(..)underset(..)N:harr:overset(1-)overset(..)N=overset(+)N=overset(1-)overset(..)N:`
The `(N_3)^(-)` ion is considered as a pseudohalide ion. It forms the extremely unstable and explosive compounds as fluorazide `FN_3`, chlorazide `CIN_3`, bromazide `BrN_3` and iodazide `IN_3`, but the dimer `N_3-N_3` is unknown.