Concept:At the anode, oxidation always takes place, which means loss of electrons.
Explanation:Oxidation is defined as the loss of electrons.
Therefore, the reaction possible at the anode must have electrons on the product side.
Check each option for electron loss:
Option A:
F2+2e−→2 F− — electrons are gained, so it is reduction.
Option B:
2H++21O2+2e−→H2O — electrons are gained, so it is reduction.
Option C:
Fe2+→Fe3++1e− —
Fe2+ loses one electron to form
Fe3+, so it is oxidation.
Option D:
Cu2++2e−→Cu(s) — electrons are gained, so it is reduction.
Thus, the only oxidation reaction is given by Option C.
Answer:Option C:
Fe2+→Fe3++1e−