Indigo shows cis-trans isomerism. Which is the stable form of Indigo

Options

A. Either cis or trans
B. Trans
C. Cis
D. Both of the above

Explanation

To determine the stable form of indigo, we need to analyze its isomerism, specifically the cis and trans forms.

### Step-by-Step Solution:

1. **Understanding Indigo Structure**:
Indigo is an organic compound that can exist in two geometric isomers: cis and trans. These isomers differ in the spatial arrangement of their atoms around a double bond.

2. **Identifying Isomers**:
- **Cis Isomer**: In the cis form, the substituents are on the same side of the double bond.
- **Trans Isomer**: In the trans form, the substituents are on opposite sides of the double bond.

3. **Analyzing Stability**:
- The stability of isomers can be influenced by steric hindrance and torsional strain. In the case of indigo, the trans isomer is generally more stable than the cis isomer.
- This is because in the trans configuration, the bulky groups are farther apart from each other, which minimizes steric repulsion.

4. **Conclusion**:
- The trans form of indigo is the more stable isomer due to minimized steric repulsion between the substituents.

### Final Answer:
The stable form of indigo is the trans isomer.