Answer: The atom which gains electrons is sulfur
Step-by-step explanation:
Oxidation reaction is defined as the chemical reaction in which an atom looses its electrons. The oxidation number of the atom gets increased during this reaction.
![X\rightarrow X^(n+)+ne^-](https://img.qammunity.org/2020/formulas/chemistry/high-school/rx48t8e6ti747hbz5tb9q7mr6azq014cgr.png)
Reduction reaction is defined as the chemical reaction in which an atom gains electrons. The oxidation number of the atom gets reduced during this reaction.
![X^(n+)+ne^-\rightarrow X](https://img.qammunity.org/2020/formulas/chemistry/high-school/4gv8126h9h4yuw5jt1t2yx442x3hqjkxr1.png)
For the given chemical equation:
![Mg+S\rightarrow MgS](https://img.qammunity.org/2020/formulas/chemistry/high-school/bnn9fvluw4tzijshgud2zjg10e56mcsbuu.png)
Oxidation half reaction:
![Mg\rightarrow Mg^(2+)+2e^-](https://img.qammunity.org/2020/formulas/chemistry/middle-school/cx03ntgcaqybz086tb7an1hzwa8oxb6ow5.png)
Reduction half reaction:
![S+2e6-\rightarrow S^(2-)](https://img.qammunity.org/2020/formulas/chemistry/high-school/rpdyxqukqtbvdzose1socxp70ujp6yvsyn.png)
Hence, the atom which gains electrons is sulfur