Which of the following molecule is incapable of forming zwitter ion ?

Options

A. Glycine
B. Alanine
C. Valine
D. Picric acid

Answer

To determine which molecule is incapable of forming a zwitterion, we need to understand what a zwitterion is and analyze the given options.

### Step-by-Step Solution:

1. **Understanding Zwitterions**:
- A zwitterion is a molecule that has both positive and negative charges but is overall electrically neutral. This condition typically occurs in amino acids at their isoelectric point, where the amino group (-NH3+) is protonated and the carboxyl group (-COO-) is deprotonated.

2. **Identifying the Options**:
- The question provides four molecules: glycine, alanine, valine, and picric acid. We need to analyze each one to see if they can form zwitterions.

3. **Analyzing Glycine**:
- Glycine is the simplest amino acid with both an amino group and a carboxyl group. At its isoelectric point, it can exist as a zwitterion. Therefore, glycine can form a zwitterion.

4. **Analyzing Alanine**:
- Alanine, like glycine, has an amino group and a carboxyl group. It can also exist as a zwitterion at its isoelectric point. Therefore, alanine can form a zwitterion.

5. **Analyzing Valine**:
- Valine is another amino acid with an amino group and a carboxyl group. It too can exist as a zwitterion at its isoelectric point. Therefore, valine can form a zwitterion.

6. **Analyzing Picric Acid**:
- Picric acid is a strong acid and does not have the structure of an amino acid. It does not possess both an amino group and a carboxyl group in a way that allows it to form a zwitterion. Therefore, picric acid cannot form a zwitterion.

7. **Conclusion**:
- Among the given options, picric acid is the molecule that is incapable of forming a zwitterion.

### Final Answer:
**Picric acid is incapable of forming a zwitterion.**

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