The equation which is balanced and represents the correct product(s) is:

$\displaystyle \mathrm{Li}_2 \mathrm{O}+2 \mathrm{KCl} \rightarrow 2 \mathrm{LiCl}+\mathrm{K}_2 \mathrm{O}$

$\displaystyle \begin{aligned} & {\left[\mathrm{CoCl}\left(\mathrm{NH}_3\right)_5\right]^{+}+5 \mathrm{H}^{+} \rightarrow \mathrm{Co}^{2+}} \\ & +5 \mathrm{NH}_4^{+}+\mathrm{Cl}^{-} \end{aligned}$

$\displaystyle \begin{aligned} & {\left[\mathrm{Mg}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{2+}+(\mathrm{EDTA})^{4-}} \\ & \xrightarrow{\text { excess } \mathrm{NaOH}}\left[\mathrm{Mg}(\mathrm{EDTA})\right]^{2+}+6 \mathrm{H}_2 \mathrm{O} \end{aligned}$

$\displaystyle \begin{aligned} & \mathrm{Cu} \mathrm{SO}_4+4 \mathrm{KCN} \rightarrow \mathrm{~K}_2\left[\mathrm{Cu}(\mathrm{CN})_4\right] \\ & +\mathrm{K}_2 \mathrm{SO}_4 \end{aligned}$