Answer:
Hydrogen gas is produced.
Explanation:
Generally when metals react with acid they gives metallic salt along with the evolution hydrogen gas.
So, when magnesium metal is added to hydrochloric acid it gives magnesium chloride and hydrogen gas as a product.
[tex]Mg(s)+2HCl(aq)\rightarrow MgCl_2(aq)+H_2(g)[/tex]
