Which of the following statement is incorrect ?

Options

A. A meso compound has chiral centres but does not exhibit optical activity.
B. If a molecule is dissymmetric, it rotate the plane of plane polarized light.
C. A meso compound is optically inactive because the rotation caused by any molecule is cancelled by an equal and opposite rotation caused by another molecule that is the mirror image of the first.
D. The twc diastereomers have same structure formula but different physical and chemical properties

Explanation

To determine which statement is incorrect regarding meso compounds and their optical activity, we need to analyze the provided statements.

### Step-by-Step Solution:

1. **Understanding Meso Compounds**:
- Meso compounds are a type of stereoisomer that has multiple chiral centers but is achiral due to an internal plane of symmetry. This means that they do not exhibit optical activity.

2. **Analyzing the Statements**:
- We need to evaluate the statements given in the question. Since only one statement is mentioned in the transcript, we will focus on that.

3. **Evaluating the Third Statement**:
- The third statement claims that "meso compounds are optically inactive because the rotation caused by the molecule is cancelled by equal and opposite rotation caused by another molecule that is in mirror image of the first."
- This statement is misleading because it implies that meso compounds are optically inactive due to interactions with their mirror images, which is not the case. Meso compounds are inherently optically inactive due to their internal symmetry, not because of interactions with other molecules.

4. **Correct Understanding**:
- The correct reason for the optical inactivity of meso compounds is due to internal compensation of optical rotation, not due to the presence of a mirror image molecule. Therefore, the third statement is indeed incorrect.

### Conclusion:
The incorrect statement is the third one, which misrepresents the reason for the optical inactivity of meso compounds.

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