Among the following the optically inactive compound is :

Options

A.
B.
C.
D.

Answer

To determine which among the given compounds is optically inactive, we need to analyze the presence of a plane of symmetry in each compound. A compound is optically inactive if it possesses a plane of symmetry, which means it can be superimposed on its mirror image.

### Step-by-Step Solution:

1. **Understand Optical Activity**:
- Optical activity refers to the ability of a compound to rotate plane-polarized light. A compound is optically active if it lacks a plane of symmetry and has chiral centers.

2. **Identify the Compounds**:
- We need to analyze the provided compounds to check for the presence of a plane of symmetry.

3. **Analyze Each Compound**:
- **Compound A**: If nitrogen has three different groups and a lone pair, it does not have a plane of symmetry. Thus, it is optically active.
- **Compound B**: Similar to compound A, if phosphorus has three different groups and a lone pair, it also lacks a plane of symmetry and is optically active.
- **Compound C**: This compound has a double bond and is planar. However, if there are two different groups on each carbon of the double bond, it may not have a plane of symmetry. It needs to be analyzed further.
- **Compound D**: If there are four different groups attached to a carbon atom, it lacks a plane of symmetry, making it optically active.

4. **Determine the Optically Inactive Compound**:
- After analyzing the compounds, we find that compound C, despite being planar, does not have a plane of symmetry due to the arrangement of groups around the double bond. However, if it has a symmetrical arrangement, it could be optically inactive.
- If we conclude that compound C has a plane of symmetry, it would be the optically inactive compound among the options.

5. **Conclusion**:
- The optically inactive compound is **Compound C** (assuming it has a plane of symmetry).