What is the oxidation state of an individual sulfur atom in SO_4^{2-}?

• A. -2
• B. 0
• C. +6
• D. +4

Answer: (C)

Verified step by step guidance

1. Identify the overall charge of the polyatomic ion SO_4^{2-}, which is -2.
2. Recall that oxygen almost always has an oxidation state of -2 in compounds.
3. Since there are 4 oxygen atoms, calculate the total oxidation contribution from oxygen: 4 \times (-2) = -8.
4. Let the oxidation state of sulfur be x. Write the equation for the sum of oxidation states equal to the overall charge: x + (-8) = -2.
5. Solve for x: x = -2 + 8, which gives the oxidation state of sulfur.