Which pair show cis-trans isomerism

Options

A. Maleic-fumaric acid
B. Lactic-tartaric acid
C. Malonic-succinic acid
D. Crotonic-acrylic acid

Explanation

To determine which pair shows cis-trans isomerism, we need to analyze the given options. Cis-trans isomerism, also known as geometric isomerism, occurs in compounds with restricted rotation around a double bond or within a ring structure, where substituents can be arranged differently in space.

### Step-by-Step Solution:

1. **Identify the Options**: The question provides four pairs of acids:
- Option 1: Maleic acid and Fumaric acid
- Option 2: Electric tetrac acid
- Option 3: Melonic acid and Succinic acid
- Option 4: Crotonic acid and Acrylic acid

2. **Understanding Maleic and Fumaric Acids**:
- Maleic acid (cis) has both carboxylic acid groups (–COOH) on the same side of the double bond, leading to a cis configuration.
- Fumaric acid (trans) has the carboxylic acid groups on opposite sides of the double bond, leading to a trans configuration.

3. **Analyzing Other Options**:
- **Electric Tetrac Acid**: This name does not correspond to a known compound, so we cannot analyze it.
- **Melonic Acid and Succinic Acid**: Both of these acids do not have a double bond that allows for cis-trans isomerism.
- **Crotonic Acid and Acrylic Acid**: Crotonic acid can exhibit cis-trans isomerism due to its double bond, but acrylic acid does not have a geometric isomer.

4. **Conclusion**: The only pair that exhibits cis-trans isomerism is Maleic acid (cis) and Fumaric acid (trans). Therefore, the correct answer is Option 1.

### Final Answer:
The pair that shows cis-trans isomerism is **Maleic acid and Fumaric acid**.