What is meant by a `1^@` carbon atom ?

Explanation

### Step-by-Step Solution:

1. **Definition of a 1° Carbon Atom**: A 1° (one degree) carbon atom, also known as a primary carbon atom, is defined as a carbon atom that is bonded to only one other carbon atom.

2. **Example Structure**: Consider the hydrocarbon structure CH3-CH-CH2-CH3. In this structure:
- The first carbon (CH3) is connected to one carbon atom (the second carbon).
- The second carbon (CH) is connected to one carbon atom (the first carbon) and one hydrogen atom.
- The third carbon (CH2) is connected to two carbon atoms (the second and fourth carbons).
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