Why do aliphatic aldehydes not show chain isomerism?

Explanation

### Step-by-Step Solution:

1. **Understanding Aldehydes**: Aldehydes are organic compounds that contain a carbonyl group (C=O) with the carbon atom of the carbonyl group bonded to at least one hydrogen atom. The general formula for aliphatic aldehydes is RCHO, where R is an alkyl group.

2. **Definition of Chain Isomerism**: Chain isomerism occurs when compounds have the same molecular formula but differ in the arrangement of the carbon skeleton. This means that the carbon chain can be arranged in different ways (e.g., straight-chain vs. branched-chain).

3. **Numbering of Carbon Atoms**: In aldehydes, the carbonyl group is always at the end of the carbon chain. The carbon atom of the carbonyl group is designated as carbon 1. This means that the numbering of the carbon chain always starts from the aldehyde carbon.

...