Short answer: The parts are not completely integrated, these can be easily separated and the properties are not uniform
Step-by-step explanation:
A pizza is a mixture because it includes multiple parts of ingredients such as cheese, pepperoni, dough, tomato sauce, etc. Additionally, in a pizza, the ingredients or parts are not completely integrated. For example, at the simple sight, you can see ingredients such as the cheese or the dought separately. This is one of the most important features of heterogenous mixtures because these are never uniform.
Moreover, this lack of uniformity makes it possible to separate ingredients through physical means; for example, by separating the pepperoni with fingers. Also, in these mixtures properties are not constant; for example, different slices of pizza contain different ratios of ingredients, and some of these are liquid, while some are solid.