1. CaCO3   water   potassium hydroxide   calcium carbonate   hydrogen peroxide   Hint Hint       2. (NH4)2SO4   ammonia   ammonium sulfate   potassium permanganate   copper sulfate   Hint       3. KNO3   sodium hydroxide   sulfur dioxide   water   potassium nitrate   Hint       4. CO2   carbon disulfide   magnesium oxide   potassium hydroxide   carbon dioxide   Hint       5. KMnO4   ammonia   potassium permanganate   magnesium oxide   hydrogen peroxide   Hint       6. H2O2   copper sulfate   sulfur dioxide   carbon disulfide   hydrogen peroxide   Hint       7. H2SO4   sulfuric acid   sodium chloride   potassium nitrate   copper sulfate   Hint