Adding a certain amount of iron powder into the mixed solution of AglO 3 and Cu(lO 3) 2, iron will first react with silver nitrate to produce ferrous nitrate and silver, and then react with copper nitrate to produce ferrous nitrate and copper, that is, Fe+2AglO 3 =Fe(lO 3) 2 +2Ag, Fe+Cu(lO 3) 2 =Fe(lO 3) 2 +Cu, and then react with copper nitrate. There is white precipitation, which means that the filtrate contains silver nitrate, that is, the added iron only reacts with part of silver nitrate, and the precipitated solid is silver, with no copper precipitation and no iron residue. Observe the options, so choose B.