Which of the following statements is correct for the complex $\left[\mathrm{Cr}{\left({\mathrm{H}}_2\mathrm{O}\right)}_6\right]{\mathrm{Cl}}_3$?

Explain, by referring to successive ionization energies, why $\mathrm{Ti}$ forms variable oxidation states, but $\mathrm{Ca}$ only occurs in the $+2$ oxidation state.

Consider the complex, ${\mathrm{K}}_4\left[\mathrm{Fe}{\left({\mathrm{C}}_2{\mathrm{O}}_4\right)}_3\right]$. Deduce the condensed electron configuration of the transition metal in this complex.

Consider the complex, ${\mathrm{K}}_4\left[\mathrm{Fe}{\left({\mathrm{C}}_2{\mathrm{O}}_4\right)}_3\right]$. State the geometry of the transition metal complex and draw a diagram of the complex.

Consider the complex, ${\mathrm{K}}_4\left[\mathrm{Fe}{\left({\mathrm{C}}_2{\mathrm{O}}_4\right)}_3\right]$. Identify the nature of the bonding between the ligand and the transition metal ion in the complex.