The alkene that exhibits geometrical isomerism is

Options

A. propene
B. 2-methyl propene
C. 2-butene
D. 2-methyl-2-butene

Answer

To determine which alkene exhibits geometrical isomerism, we need to analyze each option based on the structural requirements for geometrical (cis-trans) isomerism. Geometrical isomerism occurs when there is a double bond between two carbon atoms, and each carbon atom of the double bond must have two different substituents.

### Step-by-Step Solution:

1. **Analyze Option A: Propene**
- Structure: Propene (C3H6) has the structure CH2=CH-CH3.
- Check the double bond: The double bond is between the first and second carbon atoms.
- Substituents: The first carbon (C1) has two hydrogen atoms (H) and the second carbon (C2) has one hydrogen and one methyl group (CH3).
- Conclusion: Since C1 has two identical substituents (H), propene cannot exhibit geometrical isomerism.

2. **Analyze Option B: 2-Methylpropene**
- Structure: 2-Methylpropene (C4H8) has the structure CH2=C(CH3)-CH3.
- Check the double bond: The double bond is between the first carbon (C1) and the second carbon (C2).
- Substituents: C1 has two hydrogen atoms (H) and C2 has two methyl groups (C).
- Conclusion: Since C1 has two identical substituents (H) and C2 has two identical substituents (C), 2-methylpropene cannot exhibit geometrical isomerism.

3. **Analyze Option C: 2-Butene**
- Structure: 2-Butene (C4H8) has the structure CH3-CH=CH-CH3.
- Check the double bond: The double bond is between the second carbon (C2) and the third carbon (C3).
- Substituents: C2 has one methyl group (CH3) and one hydrogen (H), while C3 also has one methyl group (CH3) and one hydrogen (H).
- Conclusion: Both C2 and C3 have different substituents (H and CH3), allowing for the possibility of cis (same side) and trans (opposite side) configurations. Thus, 2-butene can exhibit geometrical isomerism.

4. **Analyze Option D: 2-Methyl-2-butene**
- Structure: 2-Methyl-2-butene (C5H10) has the structure CH3-C(CH3)=CH-CH3.
- Check the double bond: The double bond is between C2 and C3.
- Substituents: C2 has two methyl groups (C) and C3 has one methyl group (C) and one hydrogen (H).
- Conclusion: Since C2 has two identical substituents (C), 2-methyl-2-butene cannot exhibit geometrical isomerism.

### Final Answer:
The alkene that exhibits geometrical isomerism is **Option C: 2-butene**.