Which of the following metals will be oxidized by Co^{2+} ions in an aqueous solution?

• A. Fe
• B. Zn
• C. Cu
• D. Ag

Answer: (B)

Verified step by step guidance

1. Understand the concept of oxidation and reduction in terms of redox reactions: a metal will be oxidized if it can lose electrons to another species that is reduced. Here, Co^{2+} ions act as the oxidizing agent and will be reduced by gaining electrons.
2. Recall that whether a metal is oxidized by Co^{2+} depends on the relative standard reduction potentials (E^{\circ}) of the metal and Co^{2+}. The metal must have a lower (more negative) reduction potential than Co^{2+} to be oxidized by it.
3. Look up the standard reduction potentials for the half-reactions: \(\text{Co}^{2+} + 2e^- \rightarrow \text{Co}\), \(\text{Fe}^{2+} + 2e^- \rightarrow \text{Fe}\), \(\text{Zn}^{2+} + 2e^- \rightarrow \text{Zn}\), \(\text{Cu}^{2+} + 2e^- \rightarrow \text{Cu}\), \(\text{Ag}^{+} + e^- \rightarrow \text{Ag}\).
4. Compare the reduction potentials: if the metal's reduction potential is lower than that of Co^{2+}, the metal can be oxidized by Co^{2+} ions (meaning the metal will lose electrons and Co^{2+} will gain them).
5. Identify which metal(s) have lower reduction potentials than Co^{2+}. The metal(s) with lower reduction potentials will be oxidized by Co^{2+} ions in aqueous solution.