Which of the following represents a process in which a species is reduced?

• A. Cu^{2+} ightarrow Cu + 2e^-
• B. Zn ightarrow Zn^{2+} + 2e^-
• C. Cl_2 ightarrow 2Cl^-
• D. Fe^{3+} + e^- ightarrow Fe^{2+}

Answer: (D)

Verified step by step guidance

1. Recall that reduction is defined as the gain of electrons by a species. In other words, the oxidation state of the species decreases during reduction.
2. Examine each given process and identify whether electrons are gained or lost by the species on the left side of the equation.
3. For the process \(Cu^{2+} \rightarrow Cu + 2e^-\), the copper ion loses 2 electrons to form neutral copper metal, indicating oxidation, not reduction.
4. For the process \(Zn \rightarrow Zn^{2+} + 2e^-\), zinc metal loses 2 electrons to form zinc ion, which is also oxidation.
5. For the process \(Cl_2 \rightarrow 2Cl^-\), chlorine molecules gain electrons to form chloride ions, which is a gain of electrons and therefore a reduction process.