Balance the following chemical equation and identify the type of chemical reaction.
a) ` Mg(s) + Cl_2 (g) to MgCl_2 (s)`
b) `HgO(s) to overset("heat")(to) Hg(l) + O_2 (g) uarr`
c)`Na(s) + S(s) overset("heat")(to) Na_2S (s)`

Explanation

It is a combination reaction. b) It is a thermal decomposition reaction. c) It is a combination reaction.