Why is milk regarded as a mixture and not a pure substance?

Hint – In this question use the concept that milk is a mixture of water, fat, solids in the form of milk proteins and even carbohydrates. Application of this along with the basic definition of mixture and a pure substance will find the right reason why milk is a mixture. Complete answer: As we know that the pure substances are either elements or compounds while the mixture is a resultant product of any two or more than two substances. Now as we know that we get milk from the cow and it is a mixture of water, fat and solids (in the form of milk protein and carbohydrates) which is mixed irrationally. Therefore milk is a mixture not a pure substance. Main compounds of milk are lactose and casein. And it is also called a colloidal mixture (i.e. in which one substance of microscopically dispersed insoluble or soluble particles is suspended throughout another substance). Therefore milk is regarded as a mixture not as a pure substance. So this is the required answer. Note – The basic definition of pure substance is that they are substances that are made up of only one type of atom or molecule. The physical properties of a pure substance include a well-defined melting and boiling points. Mixtures can be considered as a combination of different things in which the component elements are individually distinct.