(A) : Amino acids are least solute in water when pH is equal to pI.
(R ) : At isoelectric point, the covalency of amino acid dominates.

Options

A. Both (A) and (R ) are true and (R ) is the correct explanation of (A)
B. Both (A) and (R ) are true and (R ) is not the correct explanation of (A)
C. (A) is true but (R ) is false
D. (A) is false but (R ) is true

Answer

To analyze the statements provided in the question, we will break down the concepts of amino acids, their solubility in water, and the isoelectric point (pI).

### Step-by-Step Solution:

1. **Understanding Amino Acids and pI**:
- Amino acids are the building blocks of proteins and contain both an amino group (-NH2) and a carboxyl group (-COOH).
- The isoelectric point (pI) is the pH at which an amino acid has no net charge. This occurs when the positive and negative charges balance each other out.

**Hint**: Recall that the pI is a specific pH where the overall charge of the amino acid is neutral.

2. **Solubility of Amino Acids**:
- The solubility of amino acids in water is influenced by their charge. When an amino acid is charged (either positive or negative), it can interact with water molecules, making it more soluble.
- At the isoelectric point, the amino acid has no net charge, which means it cannot effectively interact with water, leading to decreased solubility.

**Hint**: Consider how charge affects interactions with polar solvents like water.

3. **Analyzing Statement (A)**:
- Statement (A) claims that amino acids are least soluble in water when pH equals pI. This is true because at pI, amino acids do not have a net charge to facilitate solubility.

**Hint**: Think about how the absence of charge affects solubility.

4. **Analyzing Statement (R)**:
- Statement (R) claims that at the isoelectric point, the covalency of amino acid dominates. This is misleading. While covalent bonds are present in the structure of amino acids, the key factor affecting solubility at pI is the absence of net charge, not covalency.

**Hint**: Reflect on the role of charge versus covalency in solubility.

5. **Conclusion**:
- Based on the analysis, Statement (A) is true, while Statement (R) is false. Thus, the correct answer is that A is true, but R is false.

**Hint**: Review the definitions of true and false statements in context to understand their implications.

### Final Answer:
- **(A)** is true: Amino acids are least soluble in water when pH equals pI.
- **(R)** is false: At isoelectric point, the covalency of amino acid does not dominate; rather, the lack of net charge is the critical factor.