Answer
a) $K^+, I^-$
b) $Mg^{2+}, 2\ CH_3CO_2^{-}$
c) $2\ K^+, HPO_4^{2-}$
d) $Na^+, CN^{-}$
Work Step by Step
This problem requires familiarization with common ions,
a) $K^+, I^-$
b) $Mg^{2+}, 2\ CH_3CO_2^{-}$
c) $2\ K^+, HPO_4^{2-}$
d) $Na^+, CN^{-}$