Geometrical isomerism is due to -

Options

A. The resticted rotation about a double bond
B. The presence of keto group
C. The presence of CH(OH) group
D. The presence of an asymmetric carbon

Answer

To answer the question "Geometrical isomerism is due to -", we need to understand the concept of geometrical isomerism and the conditions that lead to its occurrence.

### Step-by-Step Solution:

1. **Definition of Geometrical Isomerism**:
Geometrical isomerism refers to the existence of compounds that have the same molecular formula and sequence of bonded atoms (connectivity) but differ in the spatial arrangement of these atoms. This type of isomerism is often observed in compounds with restricted rotation.

2. **Conditions for Geometrical Isomerism**:
Geometrical isomerism typically occurs in:
- **Alkenes**: Compounds with carbon-carbon double bonds (C=C) where rotation around the double bond is restricted.
- **Cyclic Compounds**: Rings that prevent rotation due to their structure.

3. **Types of Geometrical Isomers**:
The two main types of geometrical isomers are:
- **Cis Isomers**: The substituents are on the same side of the double bond or ring.
- **Trans Isomers**: The substituents are on opposite sides of the double bond or ring.

4. **Explanation of the Statements**:
- **Statement 1**: "The restriction of rotation about a double bond" - This is correct as it directly relates to the existence of geometrical isomers.
- **Statement 2**: "Presence of Keto group" - This is incorrect as the presence of a keto group does not inherently lead to geometrical isomerism.
- **Statement 3**: "The presence of CH OH group" - This is also incorrect because the presence of a hydroxyl group does not restrict rotation in a way that leads to geometrical isomers.
- **Statement 4**: "The presence of Asymmetrical Carbon" - This is incorrect because asymmetrical (chiral) carbons lead to optical isomerism, not geometrical isomerism.

5. **Conclusion**:
The correct answer is that geometrical isomerism is due to the restriction of rotation about a double bond.

### Final Answer:
Geometrical isomerism is due to the restriction of rotation about a double bond.

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