Geometrical isomerism results because molecule has

Options

A. A centre of symmetry
B. A plane of symmetry
C. The capacity to rotate the plane of polarized light
D. Two dissimilar groups attached to a double bond carbon atom

Explanation

To determine why geometrical isomerism occurs in certain molecules, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Geometrical Isomerism**:
Geometrical isomerism is a type of stereoisomerism that arises due to the different spatial arrangements of groups around a double bond or a ring structure.

2. **Identify the Requirement for Geometrical Isomerism**:
For geometrical isomerism to occur, there must be a carbon-carbon double bond (C=C) or a cyclic structure. This is because the double bond or the ring restricts rotation, leading to distinct configurations.

3. **Check for Dissimilar Groups**:
At least one of the carbon atoms involved in the double bond must be bonded to two different groups (dissimilar groups). For example, if we have a double bond between two carbon atoms, one carbon might be attached to a methyl group (CH₃) and a chlorine atom (Cl), while the other carbon is attached to a hydrogen atom (H) and another methyl group (CH₃).

4. **Identify the Isomers**:
The two main types of geometrical isomers are:
- **Cis Isomer**: The two similar groups are on the same side of the double bond.
- **Trans Isomer**: The two similar groups are on opposite sides of the double bond.

5. **Conclusion**:
Therefore, geometrical isomerism results because the molecule has at least one carbon-carbon double bond with two dissimilar groups attached to the carbon atoms involved in the double bond.

### Final Answer:
Geometrical isomerism results because the molecule has a carbon-carbon double bond with two dissimilar groups attached to it.

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