Assuming that \( \mathrm{Ba(OH)_2} \) is completely ionised in aqueous solution under the given conditions the concentration of \( \mathrm{H_3O^+} \) ions in \( 0.005 \, \text{M} \) aqueous solution of \( \mathrm{Ba(OH)_2} \) at \( 298 \, \text{K} \) is _______ \( \times 10^{-12} \) \( \text{mol L}^{-1} \). (Nearest integer)
