The Lanthanoid ion which would form coloured compounds is -------------.

Atomic numbers: $$\mathrm{Yb}=70, \quad \mathrm{Lu}=71, \mathrm{Pr}=59, \quad \mathrm{La}=57$$

The metallic ions that have almost same spin only magnetic moment are :

(i) $$\mathrm{Co}^{2+}$$

(ii) $$\mathrm{Mn}^{2+}$$

(iii) $$\mathrm{Cr}^{2+}$$

(iv) $$\mathrm{Cr}^{3+}$$

The correct order of increasing melting point is

Consider the following statements in respect of lanthanides, which of the statements are incorrect?

(i) $$\mathrm{La}(\mathrm{OH})_3$$ is least basic among the hydroxides of lanthanides

(ii) The lanthanide ions $$\mathrm{Yb}^{2+}, \mathrm{Lu}^{3+}$$ and $$\mathrm{Ce}^{4+}$$ are diamagnetic in nature.

(iii) $$\mathrm{Ce}^{4+}$$ can act as an oxidising agent

(iv) $$\operatorname{Ln}$$ (III) compounds are generally colourless

(v) Ionic radii of $$\mathrm{Ce}^{3+}$$ is greater than $$\mathrm{Yb}^{3+}$$