What is the number of structural isomers of monohalogenated n-butane?

Explanation

To determine the number of structural isomers of monohalogenated n-butane, we can follow these steps:

### Step 1: Understand the structure of n-butane
n-butane is a straight-chain alkane with the molecular formula C4H10. Its structure can be represented as:
\[ \text{CH}_3\text{CH}_2\text{CH}_2\text{CH}_3 \]

### Step 2: Identify the monohalogenated compound
When we replace one hydrogen atom in n-butane with a halogen (let's take chlorine as an example), the molecular formula becomes C4H9Cl.
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