A) A 1.00 L solution contains 2.75×10^-4 M Cu(NO3)2 and 2.20×10^-3 M ethylenediamine (en). The Kf for Cu(en)2^2+ is 1×10^20. What is the concentration of Cu^2+ (aq) in the solution? B) Lead poisoning in children used to be treated with injections of EDTA. If the concentration of EDTA in the blood of a patient is 2.85×10^-8 M and the formation constant for the complex, [Pb(EDTA)]^2-, is 2.00×10^18, what is the concentration ratio of the free Pb^2+ (aq) in the blood to the much less toxic Pb^2+ – EDTA complex?