the acidic group in aqueous solution of glycine is

Options

A. `-COOH`
B. `-COO^(-)`
C. `-NH_2`
D. `-NH_3^(+)`

Answer

To determine the acidic group in the aqueous solution of glycine, we need to analyze the structure and functional groups present in glycine.

### Step-by-Step Solution:

1. **Understand the Structure of Glycine**:
- Glycine is the simplest amino acid with the formula C₂H₅NO₂. It contains an amino group (-NH₂) and a carboxyl group (-COOH).
- The structural formula can be represented as:
```
H2N-CH2-COOH
```

2. **Identify Functional Groups**:
- In glycine, the two functional groups are:
- The amino group (-NH₂), which can accept a proton (H⁺) and act as a base.
- The carboxyl group (-COOH), which can donate a proton (H⁺) and act as an acid.

3. **Determine the Acidic Group**:
- In an aqueous solution, the carboxyl group (-COOH) can dissociate to release a proton (H⁺), forming a carboxylate ion (-COO⁻).
- Therefore, the acidic nature of glycine in an aqueous solution is attributed to the carboxyl group.

4. **Conclusion**:
- The acidic group in the aqueous solution of glycine is the carboxyl group (-COOH). When it donates a proton, it forms the carboxylate ion (-COO⁻).

### Final Answer:
The acidic group in the aqueous solution of glycine is the carboxyl group (-COOH).

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