Final answer:
In the reaction S + Cl₂ → SCl₂, sulfur is oxidized as it loses electrons and its oxidation state increases from 0 to +2. Chlorine is reduced as it gains electrons and its oxidation state decreases from 0 to -1 in the product SCl₂.
Step-by-step explanation:
The question relates to the chemical reaction S + Cl₂ → SCl₂ and which species undergoes oxidation or reduction, taking into account that chlorine is the more electronegative element. In a redox reaction, the substance that loses electrons is oxidized, while the substance that gains electrons is reduced. When sulfur reacts with chlorine to form SCl₂, sulfur starts in an oxidation state of 0 and ends up with an oxidation state of +2 in SCl₂, because it is bonded to two chlorine atoms each with an oxidation state of -1. This indicates that sulfur is giving up electrons, and therefore, sulfur is the one that undergoes oxidation. Chlorine, being the more electronegative element, undergoes a reduction because it gains electrons when it forms a bond with sulfur, going from an oxidation state of 0 in Cl₂ to -1 in SCl₂.