Observe the following reactions.

$$ \begin{aligned} & \text { I. } \mathrm{H}_2 \mathrm{O}(l)+2 \mathrm{Na}(s) \longrightarrow 2 \mathrm{NaOH}(a q)+\mathrm{H}_2(g) \\\\ & \text { II. } 2 \mathrm{H}_2 \mathrm{O}(l)+2 \mathrm{~F}_2(g) \longrightarrow 4 \mathrm{H}^{+}(a q)+4 \mathrm{~F}^{-}(a q)+\mathrm{O}_2(g) \end{aligned} $$

Which of the following is only a redox reaction but not a disproportionation reaction?