Classify the following as pure substances or mixtures, give reasons.
(i) Graphite (ii) Milk
(iii) Air (iv) Diamond

Explanation

To classify the given substances as pure substances or mixtures, we need to understand the definitions of both terms:

- **Pure Substances**: These are materials that consist of only one type of particle. They have a uniform and definite composition. Examples include elements and compounds that are homogeneous in nature.

- **Mixtures**: These consist of two or more different types of particles. They can vary in composition and do not have a fixed ratio of constituents. Mixtures can be homogeneous (uniform composition) or heterogeneous (distinct phases).

Now, let's classify each substance:

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