what is the net ionic equation to show the formation of a precipitate (insoluble salt) when the following solutions are mixed. write none if no insoluble salt forms. a)AgNo3(aq) + Na2SO4(aq). b)KCl(aq) + Pb(NO3)2(aq). c)CaCl2(aq) + (NH4)3PO4(aq). d)K2SO4(aq) + BaCl2(aq).