____________ is a colorless, odorless gas that forms when fuels are not completely burned.
Explanation:
Carbon monoxide is a toxic and flammable gas which is also colorless. Chemical formula of carbon monoxide is CO.
This gas is produced upon incomplete combustion of carbon.
For example, \(C(s) + \frac{1}{2}O_{2}(g) \rightarrow CO(g)\)
Therefore, we can conclude that carbon monoxide is a colorless, odorless gas that forms when fuels are not completely burned.