Classify the following as pure substances or mixtures. Separate the pure substances into elements, compounds and divide the mixtures into homogeneous and heterogeneous :
Air

Explanation

**Step-by-Step Solution:**

1. **Understand the Definitions**:
- **Pure Substance**: A material that consists of only one type of particle. It can be an element or a compound.
- **Element**: A pure substance that cannot be broken down into simpler substances by chemical means. It consists of only one type of atom.
- **Compound**: A pure substance formed when two or more different types of elements are chemically bonded together in a fixed ratio.
- **Mixture**: A combination of two or more substances that are not chemically bonded. Mixtures can be classified into homogeneous and heterogeneous.
- **Homogeneous Mixture**: A mixture that has a uniform composition throughout.
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