Which of the following can show optical isomersim?

Options

A. 2, 2-Dimethyl propanoic acid
B. 2-Methyl propanoic acid
C. 2-Methyl butanoic acid
D. Ethanoic acid

Answer

To determine which of the given compounds can show optical isomerism, we need to identify if there are any chiral centers present in each compound. A chiral center is typically a carbon atom that is bonded to four different substituents.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds we need to analyze are:
- 2,2-dimethylbutane
- 2-methylbutanoic acid
- Ethanoic acid

2. **Analyze 2,2-Dimethylbutane**:
- Look for chiral centers: The carbon atoms in 2,2-dimethylbutane are either bonded to two identical methyl groups or are part of a chain with no four different substituents.
- Conclusion: There are no chiral centers in 2,2-dimethylbutane, so it cannot show optical isomerism.

3. **Analyze 2-Methylbutanoic Acid**:
- Identify the carbon atoms: Focus on the carbon atom that is attached to the carboxyl group (COOH), a methyl group (CH3), an ethyl group (C2H5), and a hydrogen atom (H).
- Conclusion: This carbon atom is a chiral center because it has four different substituents, allowing for optical isomerism.

4. **Analyze Ethanoic Acid**:
- Look at the structure: The carbon in the carboxyl group is sp2 hybridized and bonded to two identical hydrogen atoms and one methyl group.
- Conclusion: There are no chiral centers in ethanoic acid, so it cannot show optical isomerism.

5. **Final Conclusion**: The only compound that can show optical isomerism is 2-methylbutanoic acid, as it contains a chiral center.

### Answer:
The compound that can show optical isomerism is **2-methylbutanoic acid**.

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