Calcium phosphate is present in tooth enamel. Its nature is

Options

A. basic
B. acidic
C. neutral
D. amphoteric

Explanation

To determine the nature of calcium phosphate, we can analyze its chemical composition and behavior in relation to acids and bases.

### Step-by-Step Solution:

1. **Identify the Chemical Formula**:
Calcium phosphate is represented by the chemical formula \( \text{Ca}_3(\text{PO}_4)_2 \).

2. **Determine the Components**:
Calcium phosphate is composed of calcium ions (\( \text{Ca}^{2+} \)) and phosphate ions (\( \text{PO}_4^{3-} \)).

3. **Analyze the Nature of the Components**:
- Calcium hydroxide (\( \text{Ca(OH)}_2 \)) is a strong base.
- Phosphoric acid (\( \text{H}_3\text{PO}_4 \)) is a weak acid.

4. **Reaction Between Acid and Base**:
When calcium hydroxide reacts with phosphoric acid, it forms calcium phosphate and water:
\[ \text{Ca(OH)}_2 + \text{H}_3\text{PO}_4 \rightarrow \text{Ca}_3(\text{PO}_4)_2 + \text{H}_2\text{O} \]
This indicates that calcium phosphate is formed from a strong base and a weak acid.

5. **Determine the Overall Nature**:
Since calcium phosphate is derived from a strong base (calcium hydroxide) and a weak acid (phosphoric acid), the resulting salt (calcium phosphate) tends to have a basic nature.

6. **Consider the pH Context**:
In the context of tooth enamel, when the pH of the mouth falls below 5.5 (due to consumption of sweets), acids can dissolve calcium phosphate from the enamel. This indicates that the enamel (which contains calcium phosphate) is basic in nature because it can resist dissolution in neutral or basic conditions.

7. **Conclusion**:
Therefore, the nature of calcium phosphate is basic.

### Final Answer:
Calcium phosphate is basic in nature.

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