The composition of water gas is:
A. $CO + {N_2}$
B. $CO + {H_2}$
C. $CO + C{O_2}$
D. $CO + C{O_2} + C{H_4}$

Hint: In this question we will use the method of preparation of Carbon Monoxide i.e. direct combination of carbon is limited supply of oxygen or air, by dehydration of formic acid with concentrated sulphuric acid at 373K.

Complete step-by-step answer:
Water gas is a mixture of synthesized gas formed from carbon monoxide and hydrogen. Synthesis gas is a valuable substance but due to its flammability and the possibility of carbon monoxide poisoning it needs careful handling. The reaction to the water gas change can be used to lower the carbon monoxide while creating additional hydrogen, resulting in water gas. Fuel gas, which mainly consists of carbon monoxide and hydrogen, created by passing steam over incandescent coal.
Synthesis gas is made by passing steam over a red-hot carbon fuel such as coke:
${H_2}O + C \to {H_2} + CO$
Hence the composition of water gas is $CO + {H_2}$.

Note: In such types of questions the properties and uses of carbon monoxide will be used that is a colorless and odorless gas and almost soluble in water. It is a powerful reducing agent and reduces almost all the metals oxides other than those of alkali and alkaline earth metals, aluminum and few transition metals. CO is used in extraction of many metals from their oxides.