Barium ions, ${\mathrm{CN}}^{-}$and $C{o}^{2+}$form a water soluble ionic complex with ${\mathrm{Ba}}^{2+}$as free cation. For a 0.01M solution of this complex osmotic pressure is observed to be equal to 0.984 atm and degree of dissociation is found to be 75%. Then find the coordination number of Co(II) in this complex. $\left(\mathrm{T}=300\mathrm{K}\right)\left(\mathrm{R}=0.082\mathrm{L}\mathrm{atm}{\mathrm{mol}}^{-1}{\mathrm{K}}^{-1}\right)$