Which from following cations forms least stable complex with same ligand?

Which of the following species is not tetrahedral?

For cell reaction,

$$ 2 \mathrm{Al}_{(\mathrm{s})}+3 \mathrm{Cu}_{(\mathrm{aq})}^{+2} \longrightarrow 2 \mathrm{Al}_{(\mathrm{aq})}^{+3}+3 \mathrm{Cu}_{(\mathrm{s})} $$

If $\Delta \mathrm{G}^{\circ}=-1158 \mathrm{~kJ}$, what is $\mathrm{E}_{\text {cell }}^{\circ}$?

Calculate the relative lowering of vapour pressure of solution containing 0.56 g nonvolatile solute in 100 g water [molar mass of solute $=60 \mathrm{~g} \mathrm{~mol}^{-1}$ ]