Which of the following will have a trans isomer?

Options

A.
B.
C.
D.

Answer

To determine which of the given compounds will have a trans isomer, we need to understand the concept of geometrical isomerism, specifically cis and trans isomerism. Here’s a step-by-step solution:

### Step 1: Understand Geometrical Isomerism
Geometrical isomerism occurs in compounds with restricted rotation around a double bond or in cyclic structures. The two types of geometrical isomers are:
- **Cis Isomer**: Similar groups are on the same side of the double bond or ring.
- **Trans Isomer**: Similar groups are on opposite sides of the double bond or ring.

### Step 2: Identify the Compounds
Let’s analyze the compounds provided in the question (assuming they are given as options). We will determine if each compound can exhibit trans isomerism.

### Step 3: Analyze Each Compound
1. **Compound 1**: CH3-C=C-CH3 (with H on one side)
- This compound can have a trans isomer because the two CH3 groups can be on opposite sides of the double bond.
- **Conclusion**: This compound exhibits trans isomerism.

2. **Compound 2**: Cl-C=C-Cl
- In this case, the two chlorine atoms can be on opposite sides of the double bond, allowing for a trans configuration.
- **Conclusion**: This compound exhibits trans isomerism.

3. **Compound 3**: Cyclohexane with two methyl groups
- If the methyl groups are positioned on opposite sides of the cyclohexane ring, this configuration represents a trans isomer.
- **Conclusion**: This compound exhibits trans isomerism.

4. **Compound 4**: A compound with two identical substituents on one side of the double bond (e.g., H-C=C-H)
- Since both substituents are identical, it cannot exhibit geometrical isomerism.
- **Conclusion**: This compound does not exhibit trans isomerism.

### Step 4: Final Answer
Based on the analysis, the compounds that exhibit trans isomerism are:
- Compound 1
- Compound 2
- Compound 3

Thus, the correct answer is that options 2, 3, and 4 will have a trans isomer.

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