Define the term 'isomers'.

Explanation

**Step-by-Step Text Solution:**

1. **Definition of Isomers**: Isomers are defined as chemical compounds that have the same molecular formula but different chemical structures.

2. **Understanding Molecular Formula**: The molecular formula represents the number and type of atoms in a molecule using their atomic symbols. For example, the molecular formula for butane is C4H10, which indicates it contains 4 carbon (C) atoms and 10 hydrogen (H) atoms.

3. **Example of Isomers**: Consider butane (C4H10). It can exist in different structural forms. One structure is CH3-CH2-CH2-CH3 (normal butane), while another structure can be 2-methylpropane (CH3-CH(CH3)-CH2-CH3). Both structures have the same molecular formula (C4H10) but differ in their arrangement of atoms.

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