The names of some compounds are given below:
(i) 5-Ethyl-3-methylheptane
(ii) 4-Isopropyl-5-sec-butyldecane
(iii) 2-Ethylpentane
Why are the given names incorrect?

Explanation

To determine why the names of the given compounds are incorrect, we will analyze each compound step by step according to IUPAC nomenclature rules.

### Step 1: Analyze 5-Ethyl-3-methylheptane
1. **Identify the longest carbon chain**: The name suggests a heptane (7 carbon atoms) backbone.
2. **Number the carbon chain**: Start numbering from the end nearest to the first substituent. If we start from the left, we get:
- 1 (ethyl), 2, 3 (methyl), 4, 5, 6, 7.
3. **Check substituent positions**: The ethyl group is on carbon 5, and the methyl group is on carbon 3.
4. **Re-evaluate the numbering**: If we number from the right, we get:
...