C) Cu+ S=Cus
Because • Copper (CU) in its elemental form has an oxidation state of .
• Sulfur (S) in its elemental form has an oxidation state of .
• In :
• Copper (Cu) must have an oxidation state of (common oxidation state for copper in compounds).
• Sulfur (S) must have an oxidation state of to balance the charges.
Here, the oxidation state of copper changes from to in the compound , and the oxidation state of sulfur changes from to . So, there is a change in oxidation states, indicating a redox reaction.
