A solution that is mixed to be 0.010M MgCl2 andalso 0.10 NH3. Ksp (Mg(OH)2) = 18. x 10^-11 , Kb (NH3) = 1.8 x 10^-5 i, The concentration of OH- available from solution is 1.3 x 10^-3M How do you know whether it is talking about the concentration of the OH in MgOH2 or NH3, cuz they give different answers and apparently they are using NH3 not mgoh2