(20 10? Students from Class One of No.2 Middle School in Hongkou District did an experiment to produce carbon dioxide gas in the laboratory. The available experimental devices are: ① Instruments A and B.. ① In the figure, A is an iron platform and B is a long-necked funnel, so the answer is: an iron platform and a long-necked funnel;

(2) When the Kipp generator produces carbon dioxide, limestone can react with dilute hydrochloric acid to produce calcium chloride, carbon dioxide and water. The chemical reaction formula is: CaCO3+2HCl═CaCl2+CO2↑+H2O, so the answer is: CaCO3+2HCl ═ CaCl2+CO2 ↑+H2O;

③ The liquid used in this experiment is dilute hydrochloric acid, which reacts with iron to generate hydrogen, which will make the prepared carbon dioxide gas mixed with hydrogen and make the prepared gas impure, so the answer is: c, iron reacts with hydrochloric acid to generate hydrogen and make the prepared carbon dioxide gas impure.