Which of the following represented the correct IUPAC names for the compounds concerned ?
(a) 2, 2-Dichloropentane or 2-Dichloropentane
(b) 2, 3-Dimethylpentane or 3, 4-Dimethylpentane
(c) 2-Bromo-4-methylpentane or
4-Bromo-2-methylpentane
(d) But-3-en-1-ol or But-4-ol-1-ene.

Explanation

To determine the correct IUPAC names for the compounds listed in the question, we will analyze each option step by step.

### Step 1: Analyze 2,2-Dichloropentane vs. 2-Dichloropentane
- **2,2-Dichloropentane** indicates that there are two chlorine atoms attached to the second carbon of a five-carbon chain (pentane).
- **2-Dichloropentane** is incorrect because it does not specify that there are two chlorine atoms at the same position. The correct name must indicate the number of substituents.
- **Conclusion**: **2,2-Dichloropentane** is the correct IUPAC name.

### Step 2: Analyze 2,3-Dimethylpentane vs. 3,4-Dimethylpentane
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