The process in which compounds are converted to oxides by heating them in air is called oxidation.

Here's why:

* Oxidation is a chemical reaction that involves the loss of electrons or an increase in oxidation state.

* When you heat a compound in air, oxygen from the air reacts with the compound.

* The oxygen atoms gain electrons from the compound, causing the compound to be oxidized.

* The result is the formation of oxides.

Example:

* When you heat iron (Fe) in air, it reacts with oxygen (O2) to form iron oxide (Fe2O3), commonly known as rust. This is an example of oxidation.

Let me know if you'd like more examples or details!