How would you balance the following equations? Then classify if it is an electron-transfer or exchange type.?

1) Mg (s)+ O2 (g) --%26gt; ____ (s)





2) Na2CO3 (s) + ___ (aq) --%26gt; NaCl(aq) + H2O (l) + ____ (g)





3) ___ (aq) + ____ (aq) --%26gt; ZnS (s) + NaCl (aq)|||2 Mg + O2 = 2 MgO





Na2CO3 + 2 HCl = 2 NaCl + H2O + CO2





Na2S + ZnCl2 = 2 NaCl + ZnS





only the first is an electron-transfer reaction