Write the structures of the following compounds :
(i) But-2-enoic acid
(ii) But-1-en-3-yne
(iii) 3, 4, 4-Trimethylhex-1-yne

Explanation

To solve the question of writing the structures of the given compounds, we will break it down step by step for each compound.

### (i) But-2-enoic acid

1. **Identify the root name**: The root "but" indicates that there are 4 carbon atoms in the compound.
2. **Identify the functional group**: The suffix "oic acid" indicates that there is a carboxylic acid group (-COOH) present.
3. **Determine the position of the double bond**: The "2-enoic" indicates that there is a double bond between the second and third carbon atoms.
4. **Construct the structure**:
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