The correct option is
B carbon monoxide and hydrogen
Water gas is a mixture of carbon monoxide and hydrogen produced from synthesis gas. Synthesis gas is a useful product, but requires careful handling due to its flammability and the risk of carbon monoxide poisoning. The water-gas shift reaction can be used to reduce the carbon monoxide while producing additional hydrogen, resulting in water gas.
Synthesis gas is made by passing steam over a red-hot carbon fuel such as coke:
H2O+C→H2+CO;(ΔH=+131kJ/mol)
The reaction is endothermic, so the fuel must be continually re-heated to keep the reaction going. In order to do this, an air stream, which alternates with the vapor stream, is introduced for the combustion of carbon to take place.
O2+C→CO2 (ΔH=−393kJ/mol)
Theoretically, to make 6 L of water gas, 5 L of air is required.
Or, alternatively, to prevent contamination with nitrogen, energy can be provided by using pure oxygen to burn carbon into carbon monoxide.
O2+2C→2CO (ΔH=−221kJ/mol)
In this case 1 L of oxygen will create 5.3 L of pure water gas.
Hence, the correct option is B