(a) (i) Describe giving reason which one of the following pairs has the property indicated : (I) $\text{Fe}$ or $\text{Cu}$ – higher melting point (II) $\text{Ti}^{3+}$ or $\text{Sc}^{3+}$ – coloured in aqueous solution (III) $\text{Cr}$ or $\text{Zn}$ – higher third ionisation enthalpy (ii) Write the ionic equations for the oxidizing action of $\text{MnO}_4^-$ in acidic medium with : (I) $\text{Fe}^{2+}$ ion (II) $\text{I}^-$ ion