Oxidation involves

In the reactions given below,identify the species undergoing oxidation and reduction:
$(i)$ $H_{2}S_{(g)} + Cl_{2(g)} \rightarrow 2HCl_{(g)} + S_{(s)}$
$(ii)$ $3Fe_{3}O_{4(s)} + 8Al_{(s)} \rightarrow 9Fe_{(s)} + 4Al_{2}O_{3(s)}$
$(iii)$ $2Na_{(s)} + H_{2(g)} \rightarrow 2NaH_{(s)}$

For the reaction $Ag_2O + H_2O + 2e^- \to 2Ag + 2OH^-$,which of the following is true?

$Zn^{2+}_{(aq)} + 2e^- \to Zn_{(s)}$. This is

In an oxidation process,the oxidation number:

Identify the correct statement for the following reaction:
$3 \ Mg + N_2 \longrightarrow Mg_3N_2$