Which of the following is not correct?

Rusting of iron is an electrochemical phenomenon in which one spot of iron acts as anode.

$\mathrm{F}\mathrm{e}\left(\mathrm{s}\right)\to \mathrm{F}{\mathrm{e}}^{2+}\left(\mathrm{a}\mathrm{q}\right)+2{\mathrm{e}}^{-}$

These electrons move through the metal and are taken up by the oxygen already dissolved in water in presence of ${\mathrm{H}}^{+}$ furnished by ${\mathrm{H}}_2\mathrm{C}{\mathrm{O}}_3$ , which is formed by the dissolution of $\mathrm{C}{\mathrm{O}}_2\left(\mathrm{g}\right)$ in water. The concentration of ${\mathrm{H}}^{+}$ depends upon the concentration of $\mathrm{C}{\mathrm{O}}_2$ in water.

Cathode ${\mathrm{O}}_2\left(\mathrm{a}\mathrm{q}\right)+4{\mathrm{H}}^{+}+4{\mathrm{e}}^{-}\to 2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

Since increase in the concentration of ${\mathrm{H}}^{+}$ results in the increase in the rate of the reaction, therefore, rusting of iron occurs quicker, when the concentration of dissolved $\mathrm{C}{\mathrm{O}}_2$ in water increases.

$\mathrm{F}{\mathrm{e}}^{2+}$ so-obtained are further oxidized to $\mathrm{F}{\mathrm{e}}_2{\mathrm{O}}_3$ by atmospheric oxygen. $\mathrm{F}{\mathrm{e}}_2{\mathrm{O}}_3$ is then hydrated to form rust.

$\mathrm{F}{\mathrm{e}}_2{\mathrm{O}}_3+\mathrm{x}{\mathrm{H}}_2\mathrm{O}\to \underset{\left(\mathrm{R}\mathrm{u}\mathrm{s}\mathrm{t}\right)}{\mathrm{F}{\mathrm{e}}_2{\mathrm{O}}_3.\mathrm{x}{\mathrm{H}}_2\mathrm{O}}$