Fill in the blanks:
$(1)$ During the reaction $CN^{-} \to CNO^{-}$,......... is added.
$(2)$ The maximum positive oxidation number for any chalcogen compound may be ......... .

(N/A) $(1)$ $2 \ e^{-}$ (as the oxidation state of $C$ changes from $+2$ to $+4$ and $N$ remains $-3$,the change is $2$ units).
$(2)$ $+6$ (chalcogens belong to group $16$ and can exhibit a maximum oxidation state of $+6$ by utilizing their $ns$ and $np$ electrons).