The degree of dissociation \\\\((\\alpha)\\\\) for water is \\\\(\\dfrac {1.9 \ imes 10^{-7}} {100}=1.9 \ imes 10^{-9}\\\\).\\\\(1\\\\) L of water (molecular mass \\\\(= 18\\\\) g/mol) weighs \\\\(1000\\\\) g.Hence, concentration of water \\\\(=\\dfrac {1000}{18}\\\\) M.The expression for the ionization constant of water is \\\\(K=\\dfrac{[H^+][OH^-]}{[H_2O]}=C (\\alpha)^2\\\\).Substituting values in the above expression, we get:\\\\(K=\\dfrac {1000}{18} \ imes (1.9 \ imes 10^{-9})^2=2.0 \ imes 10^{-16}\\\\).