Coordination number of ${\mathrm{Cu}}^{2+}\text{ in }{\mathrm{CuSO}}_4\cdot 5{\mathrm{H}}_2\mathrm{O}\text{ is }$

Salt is represented as $\left[\mathrm{Cu}{\left({\mathrm{H}}_2\mathrm{O}\right)}_4\right]{\mathrm{SO}}_4\cdot {\mathrm{H}}_2\mathrm{O}$. Four H₂O molecules are coordinated to Cu²⁺ while remaining one H₂O molecule is H-bonded to ${\mathrm{SO}}_4^{2-}$.