Electrolysis half-reactions for molten AgBr

Steps:

• In molten AgBr, Ag⁺ migrates to cathode for reduction; Br⁻ to anode for oxidation.
• Cathode reaction: Ag⁺ gains 1 electron to form Ag, so Ag⁺ + e⁻ → Ag.
• Anode reaction: 2Br⁻ lose 2 electrons to form Br₂, so 2Br⁻ → Br₂ + 2e⁻.
• Select pair with anode oxidation first, cathode reduction second, and correct stoichiometry.

Why A is correct:

• Matches anode oxidation (2Br⁻ → Br₂ + 2e⁻) and cathode reduction (Ag⁺ + e⁻ → Ag) per standard electrolytic rules.

Why the others are wrong:

• B: Anode forms Br atoms, not diatomic Br₂ as required for halide oxidation.
• C: Cathode uses 2e⁻ for Ag⁺, violating the 1:1 electron ratio in Ag⁺ reduction.
• D: Lists cathode reaction before anode, reversing the specified order.

Final answer: A