Choose from the following compounds to answer the questions below. Ba(NO3)2 CaCO3 CaO CH4 C3H8 Fe2O3 KMnO4 NaNO3 NO SO2 V2O5 Zn(NO3)2 Each of these compounds can be used once, more than once or not at all. Which compound

1. (a)is an atmospheric pollutant formed by lightning activity,[1]
2. (b)is the main constituent of natural gas,[1]
3. (c)dissolves in water to form an aqueous solution which gives a white precipitate on addition of aqueous sodium sulfate,[1]
4. (d)is a catalyst in the contact process for the manufacture of sulfuric acid,[1]
5. (e)is a product of the thermal decomposition of limestone?[1]