Halogens combine with each other to form interhalogen compounds `(XX', XX'_(3), XX'_(5) and XX'_(7))`. Halide ions often react with molecules of halogens or interhalogens to form polyhalide ions consisting either of the same halogen or of two or three different halogens. Besides these, a few othe anions are known, which do not contain any of the halogen atoms but behave like halide ions. These anions are called pseudohalides and consist of two of more atoms of which one is always a nitrogen atom.
The correct order of pseudohalide, polyhalide and interhalogen are

Options

A. `CNO^(-)`
B. `RCOO^(-)`
C. `OCN^(-)`
D. `NNN^(-)`

Answer

B

Explanation

`RCOO^(-)` does not contain a N atom and hence is not a pseudohalide.