Question

Which of the following is not a pseudo halide?

• A. $C{N}^{-}$
• B. $OC{N}^{-}$
• C. $O{H}^{-}$
• D. $SC{N}^{-}$

Answer 1

The correct option is C $O{H}^{-}$

Pseudo halides include $C{N}^{-},OC{N}^{-},SC{N}^{-}$ etc, here we see that there is always a N atom attached to each ion. This is by definition!

Obviously the $(OH{)}^{-}$ ion does not contain a Nitrogen atom. By definition, the pseudohalides are analogues to halide ions and they even resemble the halide ions' chemistry in some ways. This is not the case with the hydroxide ion!