Select the element (M) whose trihalides cannot be hydrolysed to produce an ion of the form [M(H$$_2$$O$$_6$$]$$^{3+}$$

Which of the following forms a set of complex and a double salt, respectively?

Type of isomerism exhibited by compounds $$ \left[\mathrm{Cr}\left(\mathrm{H}_2 \mathrm{O}\right)_6 \mathrm{Cl}_3,\left[\mathrm{Cr}\left(\mathrm{H}_2 \mathrm{O}\right)_5 \mathrm{Cl}_2 \mathrm{Cl}_2 \cdot \mathrm{H}_2 \mathrm{O}\right.\right.,\left[\mathrm{Cr}\left(\mathrm{H}_2 \mathrm{O}\right)_4 \mathrm{Cl}_2\right] \mathrm{Cl} .2 \mathrm{H}_2 \mathrm{O}$$ and the value of coordination number $$(\mathrm{CN})$$ of central metal ion in all these compounds, respectively is :

Homoleptic complex from the following complexes is :