Write the ring chain functional isomer of compound But-`2`-ene are?

Explanation

To find the ring-chain functional isomers of But-2-ene (C4H8), we can follow these steps:

### Step 1: Identify the structure of But-2-ene
But-2-ene is an alkene with four carbon atoms and a double bond between the second and third carbon atoms. The structure can be represented as follows:

```
CH3
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