The ionization isomer of $[Cr(H_2O)_4Cl(NO_2)]Cl$ is

For the octahedral complexes of $Fe^{3+}$ in $SCN^{-}$ (thiocyanato-$S$) and in $CN^{-}$ ligand environments,the difference between the spin-only magnetic moments in Bohr magnetons (when approximated to the nearest integer) is
[Atomic number of $Fe = 26$]

Number of complexes from the following with an even number of unpaired $d$ electrons is . . . . . . . . . .
$[V(H_2O)_6]^{3+}, \quad [Cr(H_2O)_6]^{2+}, \quad [Fe(H_2O)_6]^{3+}, \quad [Ni(H_2O)_6]^{3+}, \quad [Cu(H_2O)_6]^{2+}$
[Given atomic numbers: $V=23, Cr=24, Fe=26, Ni=28, Cu=29$]

Which one of the following is expected to be a paramagnetic complex?

Which of the following complex compounds will exhibit highest paramagnetic behaviour?
(At. No. $Ti = 22, Cr = 24, Co = 27, Zn = 30$)

Define coordination isomerism and hydrate isomerism.