`CH_(3) - CH = undersetunderset(CH_(2) -CH_(2))(|)(C)- CH_(2) - CH_(3)`
Correct IUPAC name is

Options

A. 3-ethylhex-2-ene
B. 3-ethylpent-2-ene
C. 3-ethylpent-3-ene
D. 3-propylpent-2-ene

Answer

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

### Step 1: Identify the Longest Carbon Chain
First, we need to identify the longest continuous carbon chain in the structure. In this case, we can see that the longest chain consists of 5 carbon atoms.

### Step 2: Number the Carbon Chain
Next, we need to number the carbon chain. The numbering should be done in such a way that the double bond and substituents receive the lowest possible numbers.

- If we number from left to right:
- C1: CH3
- C2: CH (double bond here)
- C3: CH2 (with an ethyl substituent)
- C4: CH2
- C5: CH3

Here, the double bond is at C2 and the ethyl group is at C3.

### Step 3: Identify the Substituents
In this structure, we have one substituent:
- An ethyl group (C2H5) at C3.

### Step 4: Write the IUPAC Name
The IUPAC name is constructed by combining the substituent name and the main chain name.

- The main chain has 5 carbon atoms, which corresponds to "pent".
- The double bond is located at C2, so we add "2" before "ene".
- The substituent is an ethyl group at C3, so we write "3-ethyl".

Putting it all together, the IUPAC name is **3-ethylpent-2-ene**.

### Final Answer
The correct IUPAC name for the compound is **3-ethylpent-2-ene**.

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