We often read the news in the newspapers that on seeing it in the morning it was found that some people were found dead in a closed room, who were sleeping by burning coal in the fireplace.
This happened because the burning of coal produces carbon monoxide, which is a toxic gas, and also a certain amount of air exchange in closed rooms. If there is one percent of carbon monoxide in the room, it can cause death.
When coke is burnt with a certain amount of air, carbon monoxide is produced.
It is colorless, odorless gas. This is why it is not easily detected. Coal gas, which is used as an industrial fuel, is also carbon monoxide.
It is used to obtain metals from metal oxides.
How can we feel the presence of carbon monoxide? Carbon monoxide burns with blue flame and gives carbon dioxide. Carbon dioxide can also be tested, which turns lime water milky.