Final answer:
Silver accessories turn black when exposed to air due to the oxidation of silver, where silver reacts with sulfur compounds, leading to the formation of silver sulfide with a dark tarnish.
Step-by-step explanation:
Why do silver accessories turn black when exposed to air? The correct answer is A) Oxidation of silver. Silver tarnishes because it reacts with sulfur compounds present in the air, particularly hydrogen sulfide (H₂S). This reaction leads to the formation of silver sulfide (Ag₂S), which has a dark, streaky black appearance on the surface of the silver object. The word equation for this chemical reaction is 2 Ag(s) + H₂S(g) → Ag₂S(s) + H₂(g). The silver atom is oxidized as it loses electrons, changing from the 0 oxidation state to the 1+ state, while sulfur is reduced as it gains electrons. This type of reaction is known as an oxidation-reduction or 'redox' reaction.