Answer :
Combustion reaction : The combustion means burning. It is defined as the reaction in which a hydrocarbon react with oxygen in the presence of air to give carbon dioxide and water vapor as a product.
The combustion of methane gives carbon dioxide and water vapor as a product but the combustion of hydrogen gives water vapor as a product.
The balanced combustion reaction of methane will be:
![CH_4(g)+O_2(g)\rightarrow CO_2(g)+H_2O(g)](https://img.qammunity.org/2019/formulas/chemistry/high-school/k5jh2vpd5t236mjee1v2qkocb64eskiwqo.png)
The balanced combustion reaction of hydrogen will be:
![H_2(g)+O_2(g)\rightarrow H_2O(g)](https://img.qammunity.org/2019/formulas/chemistry/high-school/y3a1hr5cd14mfcchb1trv75fq1ieuo0zo2.png)