A solution containing sulfide ions is added to a solution of 0.036 M Cu2+ and 0.044 M Fe2+. At what concentration of sulfide ion will a precipitate begin to form? What is the identity of the precipitate? (a) 1.4 x 10^-16 M, FeS (b) 3.6 x 10^-35 M, CuS (c) 3.6 x 10^-35 M, FeS (d) 1.4 x 10^-16 M, C