The standard electrode potential of M$$^+$$/M in aqueous solution does not depend on

The standard electrode potential of M⁺/M can be understood through the thermodynamic cycle involving the following steps:

1. Sublimation of solid metal: M(s) → M(g), requiring sublimation enthalpy ($$\Delta_{sub}H$$)

2. Ionisation of gaseous metal atom: M(g) → M⁺(g) + e⁻, requiring ionisation enthalpy ($$\Delta_{i}H$$)

3. Hydration of gaseous metal ion: M⁺(g) → M⁺(aq), releasing hydration enthalpy ($$\Delta_{hyd}H$$)

The standard electrode potential depends on all three of these steps. It does not depend on "ionisation of a solid metal atom" because this is not a physically meaningful step in the thermodynamic cycle. Ionisation occurs in the gaseous state, not the solid state.

The correct answer is Ionisation of a solid metal atom.