Which of the following is an achiral molecule?

Options

A.
B.
C.
D.

Answer

To determine which of the given molecules is achiral, we need to analyze the substituents on the chiral centers of each molecule. An achiral molecule is one that does not have a chiral center or has a plane of symmetry that makes it superimposable on its mirror image.

### Step-by-Step Solution:

1. **Understand Chiral and Achiral Molecules**:
- Chiral molecules have four different substituents attached to a carbon atom, making them non-superimposable on their mirror images.
- Achiral molecules either lack a chiral center or have a plane of symmetry.

2. **Analyze Each Option**:
- **Option 1**: Check the substituents on the carbon atoms. If they have four different groups, they are chiral; if not, they are achiral.
- **Option 2**: Repeat the analysis for this option. Identify if there are any chiral centers.
- **Option 3**: Again, check for chiral centers and the nature of the substituents.
- **Option 4**: Look for a plane of symmetry or identical substituents that would make the molecule achiral.

3. **Identify Chiral Centers**:
- For each molecule, identify if there is a carbon atom with four different substituents.
- If there is a carbon with two identical substituents, it cannot be chiral.

4. **Determine the Presence of a Plane of Symmetry**:
- If a molecule has a plane of symmetry, it is achiral, even if it has chiral centers.

5. **Conclusion**:
- After analyzing all options, identify which one does not meet the criteria for chirality.
- The correct answer is the option that is achiral due to either having no chiral centers or having a plane of symmetry.

### Final Answer:
- **Option 4** is the achiral molecule because it has a plane of symmetry, making it superimposable on its mirror image.