Here's why:

* Multiple Components: Cereal is made up of various ingredients like grains (wheat, oats, rice), sugar, nuts, dried fruit, and sometimes other additives. These ingredients are not chemically bonded together.

* Easily Separated: You can easily separate the components of cereal. For example, you could pick out the nuts or the dried fruit.

* Variable Composition: The exact composition of cereal can vary depending on the brand and type.

While cereal contains organic compounds (like carbohydrates, proteins, and fats) from the grains and other ingredients, it's not a single pure substance but rather a combination of many.