The impurities formed during the laboratory preparation of chlorine gas are removed by

The laboratory preparation of chlorine gas often produces impurities which need to be removed before the gas can be used. The question asks which substance is used to remove these impurities. The correct answer is not explicitly stated in the question, but can be determined through knowledge of chemistry. Chlorine gas is often prepared by reacting hydrochloric acid (HCl) with manganese dioxide (MnO2). However, impurities such as excess hydrochloric acid, water, and other gases may be present in the resulting gas mixture. To remove these impurities, a substance that can react with them must be used. Hydrogen peroxide (H2O2) or sodium hydroxide (NaOH) may be used to remove excess hydrochloric acid. Calcium carbonate (CaCO3) or sodium carbonate (Na2CO3) may be used to remove acidic gases such as carbon dioxide (CO2) and sulfur dioxide (SO2). Water may be removed by passing the gas through a drying agent such as concentrated sulfuric acid (H2SO4) or calcium chloride (CaCl2). Based on the given options, the most appropriate answer is "H2O".