Now, the last type of reaction we're going to look at is called a combustion reaction. And in this reaction, hydrocarbons are burned in the presence of diatomic gas or diatomic oxygen gas to form carbon dioxide and water molecules. Now, a common example is burning of methane ch four, where our X is one and Y is four in the presence of oxygen. And heat from the triangle symbolizes heat to form carbon dioxide and water molecules. Now, other types of reactions exist. Let's look at some of them.