Question 10 • Chemistry
In ZnS, sulfur has an oxidation number of −2; in ZnSO₄, it is +6, so sulfur is oxidized. Oxygen changes from 0 in O₂ to −2 in ZnSO₄, so oxygen is reduced. Because oxidation and reduction happen together, ZnS + 2 O₂ → ZnSO₄ is an oxidation-reduction reaction. The other reactions do not change the oxidation numbers of their elements.
AI-written and checked against the verified answer.