Two basic units of which all substances are made up are………………………..and……………………….. .

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question:** The question asks for the two basic units that make up all substances.

2. **Identifying the First Basic Unit:** The first basic unit of matter is the **atom**. An atom is the smallest unit of a chemical element and retains the properties of that element. It cannot be divided into smaller units by chemical means.

3. **Identifying the Second Basic Unit:** The second basic unit is the **molecule**. A molecule is formed when two or more atoms bond together. Molecules can consist of the same type of atoms (like O2) or different types of atoms (like H2O).

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