The equilibrium constant for the formation of cucn42- is 20

Question

Question 1: The solubility product, K_sp, of Cd₃(PO₄)₂ is 2.5 x 10^-33. What is the solubility (in g/L) of Cd₃(PO₄)₂ in pure water? 

Question 2: The solubility product of Cu(OH)₂ is 4.8 x 10^-20. Calculate the value of pCu²⁺, or -log[Cu²⁺], in an aqueous solution of NaOH which has a pH of 12.87 and is saturated in Cu(OH)₂. 

Question 3: The equilibrium constant for the formation of Cu(CN)₄^2- is 2.0 x 10³⁰. Calculate the value of pCu²⁺, or -log[Cu²⁺], if we were to dissolve 2.87 g of CuCl₂ in 1.000 L of a solution 0.941 M in NaCN. The addition of CuCl₂does not alter the volume (the final volume is still 1.000 L).