CH-1712

Half-equations

Chemistry · Secondary 4 · Medium · Half-equations

During electrolysis of dilute sulfuric acid using inert electrodes, a gas is produced at the cathode. Which half‑equation correctly represents the reaction at the cathode?

$2H^+(aq) + 2e^- \rightarrow H_2(g)$
$H_2(g) \rightarrow 2H^+(aq) + 2e^-$
$2H_2O(l) + 2e^- \rightarrow H_2(g) + 2OH^-(aq)$
$SO_4^{2-}(aq) + 2e^- \rightarrow SO_2(g) + 2O^{2-}(aq)$

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