A voltaic cell is made by connecting two half cells represented by half equations below:

$$\begin{aligned} & \mathrm{Sn}_{(a q)}^{2+}+2 \mathrm{e}^{-} \rightarrow \mathrm{Sn}_{(\mathrm{s})} \mathrm{E}^{\mathrm{o}}=-0.14 \mathrm{~V} \\ & \mathrm{Fe}^{3+}{ }_{(\mathrm{aq})}+\mathrm{e}^{-} \rightarrow \mathrm{Fe}^{2+}{ }_{(\mathrm{aq})} \mathrm{E}^{\mathrm{o}}=+0.77 \mathrm{~V} \end{aligned}$$

Which statement is correct about this voltaic cell?

Four half reactions I to IV are shown below:

I. $$2 \mathrm{Cl}^{-} \rightarrow \mathrm{Cl}_2+2 \mathrm{e}^{-}$$

II. $$4 \mathrm{OH}^{-} \rightarrow \mathrm{O}_2+2 \mathrm{H}_2 \mathrm{O}+2 \mathrm{e}^{-}$$

III. $$\mathrm{Na}^{+}+\mathrm{e}^{-} \rightarrow \mathrm{Na}$$

IV. $$2 \mathrm{H}^{+}+2 \mathrm{e}^{-} \rightarrow \mathrm{H}_2$$

Which two of these reactions are most likely to occur when concentrated brine is electrolysed?

Which property of transition metals enables them to behave as catalysts?

In the two tetrahedral structures of dichromate ion