Answer: B. Molten calcium chloride contains free \(\text{Ca}^{2+}\) and \(\text{Cl}^{-}\) ions only — no water and no other species are involved.
At the positive electrode (anode), chloride ions are oxidised: \(2\text{Cl}^{-} \rightarrow \text{Cl}_2 + 2\text{e}^{-}\). Two chloride ions combine to release chlorine gas plus two electrons.
At the negative electrode (cathode), calcium ions are reduced: \(\text{Ca}^{2+} + 2\text{e}^{-} \rightarrow \text{Ca}\). Calcium metal forms.
Options A and C use the wrong cation charge (\(\text{Ca}^{+}\) doesn't exist as a stable ion). Options C and D use the impossible \(\text{Cl}^{2-}\) anion — chloride is always 1−.
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