What is isomerism? Give an example.

Explanation

### Step-by-Step Solution

1. **Definition of Isomerism**:
Isomerism is a phenomenon where compounds have the same molecular formula but differ in their structure or spatial arrangement. This means that even though the compounds contain the same number and types of atoms, their arrangement leads to different properties.

2. **Types of Isomerism**:
Isomerism can be classified into two main types:
- **Structural Isomerism**: This occurs when compounds have the same molecular formula but differ in the connectivity of their atoms. For example, butane (C4H10) can exist as two structural isomers: n-butane and isobutane.
...