Which of the following will give a green hydrated ion?

Which of the following orders is correct for the property given?

Which of the following orders is correct?

Given below are two statements:
Statement $I$: The number of pairs among $[Ti^{4+}, V^{2+}], [V^{2+}, Mn^{2+}], [Mn^{2+}, Fe^{3+}]$ and $[V^{2+}, Cr^{2+}]$ in which both ions are coloured is $3$.
Statement $II$: The number of pairs among $[La^{3+}, Yb^{2+}], [Lu^{3+}, Ce^{4+}]$ and $[Ac^{3+}, Lr^{3+}]$ ions in which both are diamagnetic is $3$.
In the light of the above statements, choose the correct option from the options given below:

Which of the comparison regarding $Zn, Cd, Hg$ is/are incorrect?
$(I)$ $ZnCl_2$ is ionic whereas $CdCl_2$ and $HgCl_2$ are covalent
$(II)$ $Zn$ and $Cd$ dissolve in dilute acid $(HCl)$ liberating $H_2$ but $Hg$ cannot
$(III)$ $Zn$ and $Cd$ form white ppt. of $Zn(OH)_2$ and $Cd(OH)_2$ but $Hg$ forms coloured ppt. of $HgO$ or $Hg(OH)_2$
$(IV)$ All form $M_2^{2+}$ type ion

The transition metals have a less tendency to form ions due to