Final answer:
In the reaction Sn(s) + 2HCl(aq) → SnCl₂(aq) + H₂(g), the oxidizing agent is Option 1: HCl, as it is reduced and gains electrons during the reaction.
Step-by-step explanation:
The question asks which substance acts as the oxidizing agent in the reaction between tin (Sn) and hydrochloric acid (HCl). In the given reaction, Sn(s) + 2HCl(aq) → SnCl₂(aq) + H₂(g), tin starts as a solid metal and ends up as a +2 ion in SnCl₂. The hydrogen in HCl changes from an ionic to a gaseous state, indicating that HCl accepts electrons and is reduced, making it the oxidizing agent. Thus, the correct option is Option 1: HCl. This aligns with the general principle that very electronegative elements are good oxidizing agents, and hydrochloric acid is no exception, being composed of hydrogen and chlorine, with chlorine being a highly electronegative element.