Answer:
[tex]Mg(s)+2H^+(aq)\rightarrow Mg^{2+}(aq)+H_2(g)[/tex]
Explanation:
Hello!
In this case, since the writing of a net ionic equation first implies writing the complete molecular equation:
[tex]Mg(s)+2HCl(aq) \rightarrow MgCl_2(aq)+H_2(g)[/tex]
We can see that HCl and MgCl2 are ionized because they are aqueous, thus we write:
[tex]Mg(s)+2H^+(aq)+2Cl^-(aq) \rightarrow Mg^{2+}(aq)+2Cl^-(aq)+H_2(g)[/tex]
In such a way, we can cancel out the chloride ions as they are the spectator ones to obtain the net ionic one:
[tex]Mg(s)+2H^+(aq)\rightarrow Mg^{2+}(aq)+H_2(g)[/tex]
Best regards!
