Which of the following exhibits geometrical isomerism ?

Options

A. 1,2-Dibromopropene
B. 2,3-Diemthylbut-2-ene
C. 2,3-Dibrobut-2-ene
D. 2-Methylbut-2-ene

Explanation

To determine which of the given compounds exhibits geometrical isomerism, we need to follow these steps:

### Step 1: Understand the Conditions for Geometrical Isomerism
Geometrical isomerism (also known as cis-trans isomerism) occurs when:
1. There is a carbon-carbon double bond (C=C) in the molecule.
2. Each carbon atom involved in the double bond must be bonded to two different groups or atoms.

### Step 2: Analyze the Given Compounds
We will analyze each option to see if they meet the conditions for geometrical isomerism.

1. **1,2-Dibromopropene**:
- Structure: CH3-CH=CHBr
- The double bond is between the second and third carbon atoms (C2=C3).
- C2 is bonded to CH3 and Br, and C3 is bonded to H and Br.
- Since C2 and C3 are bonded to different groups, this compound can exhibit geometrical isomerism.

2. **2-Dibromopropene**:
- Structure: CH3-CH=CHBr
- The double bond is again between C2 and C3.
- C2 is bonded to CH3 and H, and C3 is bonded to Br and H.
- Since both C2 and C3 are not bonded to two different groups, this compound does not exhibit geometrical isomerism.

3. **2-Bromobutene**:
- Structure: CH3-CH=CHBr
- The double bond is between C2 and C3.
- C2 is bonded to CH3 and H, and C3 is bonded to Br and H.
- Similar to the previous case, this compound does not exhibit geometrical isomerism.

### Step 3: Conclusion
From the analysis, only **1,2-Dibromopropene** exhibits geometrical isomerism.

### Summary of Findings
- **1,2-Dibromopropene**: Exhibits geometrical isomerism.
- **2-Dibromopropene**: Does not exhibit geometrical isomerism.
- **2-Bromobutene**: Does not exhibit geometrical isomerism.

### Final Answer
**1,2-Dibromopropene exhibits geometrical isomerism.**

---