Names of some compounds are given. Which one is not correct according to IUPAC system ?

Options

A. `{:(" "CH_(3)),(" |"),(CH_(3)-CH_(2)-CH_(2)-CH-CH-CH_(2)CH_(3)),(" |"),(" "CH_(2)CH_(3)),(" 4-Ethyl-3-methylheptane"):}`
B. `{:(CH_(3)-CH-CH-CH_(3)),(" | |"),(" OH CH"_(3)),(" 3-Methylbutan-2-ol"):}`
C. `{:(CH_(3)-CH_(2)-C-CH-CH_(3)),(" || |"),(" "CH_(2)CH_(3)),("2-Ethyl-3-methylbut-1-ene"):}`
D. `{:(CH_(3)-C-=C-CH(CH_(3))_(2)),("4-Methylpent-2-yne"):}`

Explanation

To determine which compound name is not correct according to the IUPAC system, we will analyze each option step by step.

### Step 1: Analyze the first option
1. Identify the longest carbon chain.
2. Number the carbon atoms in the chain.
3. Identify and name the substituents (methyl and ethyl groups).
4. Write the IUPAC name based on the position of the substituents.

**Hint:** Look for the longest continuous chain of carbon atoms and prioritize substituents based on their position.

### Step 2: Analyze the second option
1. Again, identify the longest carbon chain.
2. Number the carbon atoms.
3. Identify substituents (hydroxy and methyl groups).
4. Write the IUPAC name, ensuring the hydroxy group is given priority in numbering.

**Hint:** Remember that functional groups like hydroxy have higher priority than alkyl substituents.

### Step 3: Analyze the third option
1. Identify the longest carbon chain.
2. Number the carbon atoms.
3. Identify substituents (methyl and ethyl groups).
4. Check if the naming is correct based on the positions of the substituents.

**Hint:** Pay close attention to the names given for substituents and their positions; they must match the numbering.

### Step 4: Analyze the fourth option
1. Identify the longest carbon chain.
2. Number the carbon atoms.
3. Identify substituents (methyl groups and triple bonds).
4. Write the IUPAC name, ensuring the triple bond is indicated correctly.

**Hint:** Ensure that the triple bond is correctly represented in the name and that substituents are named according to their positions.

### Conclusion
After analyzing all options, the third option is found to be incorrect because it mislabels the substituents. The correct name should reflect the actual structure with the correct substituent names and their positions.

### Final Answer
The compound name that is not correct according to the IUPAC system is the **third option**.