Milk is classified as a mixture. Unlike elements, which consist of only one type of atom, and compounds, which are made up of two or more types of atoms that are chemically bonded together, mixtures are combinations of two or more substances that are physically combined but not chemically bonded.
In the case of milk, it is composed of water, fats, proteins, lactose (a sugar), vitamins, and minerals. Each of these components retains its own properties within the mixture. For example, the fats in milk can separate and form a layer on top if left standing, while the proteins and lactose remain mixed with water.
The physical characteristics of milk can vary, such as its fat content, which leads to different types of milk like skim, whole, or cream. This variability further supports its classification as a mixture. So, overall, milk’s unique combination of substances that maintain their individual properties is what makes it a mixture, rather than an element or a compound.