Here's why:

* Combustion is a chemical process involving the rapid reaction between a substance with an oxidant, usually oxygen, to produce heat and light.

* Carbon monoxide (CO) is formed when carbon-containing fuels are burned in an environment with limited oxygen.

The general equation for carbon monoxide formation is:

2C + O₂ → 2CO

Example:

Burning wood or charcoal in a fireplace or grill can produce carbon monoxide if there is not enough oxygen present for complete combustion.

It's important to note that carbon monoxide is a highly toxic gas and can be deadly. Proper ventilation and safe burning practices are crucial to prevent carbon monoxide buildup.