Give Reasons:
(I) \( \text{Ce}^{4+} \) in aqueous solution is a good oxidising agent.
(II) The actinoid contraction is greater from element to element than lanthanoid contraction.
(III) \( E^\circ_{\text{M}^{2+}/\text{M}} \) value is more negative than expected, whereas \( E^\circ_{\text{Cu}^{2+}/\text{Cu}} \) is positive.