The elements with full $d^{10}$ electronic configuration in their " +2 " oxidation state are

The increase in the atomic radii of the third (5d) series of transition elements is very small, which may be accounted for the filling of ' $X$ ' orbitals before ${ }^{\prime} Y^{\prime}$ orbitals $X$ and $Y$ are

The valency shell electronic configuration of Cr and Cu atoms, respectively, are

Identify all the correct statements for lanthanoide contraction.

(A) The covalent properties of the lanthanoide metal hydroxides increases from La to Lu.

(B) The chemical reactivity decreases from La to Lu.

(C) $\mathrm{La}(\mathrm{OH})_3$ is more basic than $\mathrm{Lu}(\mathrm{OH})_3$.

(D) Zr and Hf have about the same radius.

(E) Separation of lanthanoides from one another is easy.