The Ks of Ag2 CrO 4 , AgCl, AgBr and AgI are respectively, 1.1×10 −12 ,1.8×10 −1,5.0×10 −13 ,8.3×10 −17 . Which one of the following salts will precipitate last if AgNO 3 solution is added to the solution containing equal moles of NaCl, NaBr, NaI and Na 2 CrO 4 ?