Correct IUPAC name for
`H_3 C - underset(underset(C_2 H_5)|)CH - underset(underset(C_2 H_5)|) CH - CH_3`
is

Options

A. 2-ethyl-3-methylpentane
B. 3, 4-dimethylhexane
C. 2-sec-butylbutane
D. 2, 3-dimethylbutane

Explanation

To determine the correct IUPAC name for the given compound, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Longest Carbon Chain**:
- The first step is to identify the longest continuous carbon chain in the compound. In this case, the longest chain contains 6 carbon atoms.

2. **Number the Carbon Chain**:
- Number the carbon atoms in the longest chain starting from the end nearest to the first substituent. Here, we can number the chain as follows:
- C1 - C2 - C3 - C4 - C5 - C6

3. **Identify the Substituents**:
- Look for any substituents attached to the main carbon chain. In this case, we have two ethyl groups (C2H5) attached to the chain.

4. **Assign Numbers to the Substituents**:
- Assign the lowest possible numbers to the substituents. The two ethyl groups are located at C3 and C4 of the main chain.

5. **Write the Name of the Compound**:
- Combine the substituent names and their positions with the name of the main chain. Since we have two ethyl groups at positions 3 and 4, we denote this as "3,4-diethyl".
- The main chain is a hexane (since it has 6 carbon atoms), so we combine this with the substituents to get the full name.

6. **Final IUPAC Name**:
- The final IUPAC name of the compound is **3,4-diethylhexane**.