Geometrical isomerism is shown by

Options

A. 2-butene
B. 2-butyne
C. 2-butanol
D. Butanal

Explanation

To determine which compounds exhibit geometrical isomerism, we need to analyze the given options based on the criteria for geometrical isomerism. Geometrical isomerism occurs in compounds with a carbon-carbon double bond (C=C) where there is restricted rotation and different substituents attached to the carbon atoms involved in the double bond.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds we need to analyze are:
- 2-butene
- 2-butyne
- 2-butanol
- Butanol

2. **Analyze 2-butene**:
- Structure: CH3-CH=CH-CH3
- It has a carbon-carbon double bond (C=C).
- There are different groups attached to the double-bonded carbons (one carbon has a methyl group and a hydrogen, and the other carbon has a methyl group and a hydrogen).
- **Conclusion**: 2-butene can show geometrical isomerism (cis and trans forms).

3. **Analyze 2-butyne**:
- Structure: CH3-C≡C-CH3
- It has a carbon-carbon triple bond (C≡C).
- In a triple bond, there is no possibility for geometrical isomerism because there is no restricted rotation around the triple bond.
- **Conclusion**: 2-butyne does not show geometrical isomerism.

4. **Analyze 2-butanol**:
- Structure: CH3-CH(OH)-CH2-CH3
- It has a single bond between the carbons and an -OH group.
- There is no carbon-carbon double bond present, so there is no restricted rotation.
- **Conclusion**: 2-butanol does not show geometrical isomerism.

5. **Analyze Butanol**:
- Structure: CH3-CH2-CH2-CH2OH
- Similar to 2-butanol, it has only single bonds and no double bonds.
- **Conclusion**: Butanol does not show geometrical isomerism.

6. **Final Conclusion**:
- Among the given compounds, only **2-butene** shows geometrical isomerism. The correct answer is option 1 (2-butene).