How many hydroxyl ions are required for the conversion: `CN_((aq))^(-)` to `CNO_((aq))^(-)`

Explanation

`CN^(-)+OH^(-)rarrCNO^(-)`
Balancing the half reaction
`CN^(-)+2OH^(-)rarrCNO^(-)+H_(2)O+2e^(-)`
Number of hydroxyl `OH^(-)` ions `= 2`