Nature of calcium phosphate present in tooth enamel is :

Question

Accepted Answer

Calcium phosphate, specifically hydroxyapatite, is the primary mineral component of tooth enamel. The nature of calcium phosphate in tooth enamel is best described as basic. Here’s why Option 3 is correct and why the other options are incorrect:

1. **Explanation for Option 3 (Basic):**
   - Calcium phosphate, in the form of hydroxyapatite, has a chemical formula of Ca₁₀(PO₄)₆(OH)₂. This compound is basic in nature because it contains phosphate ions (PO₄³⁻), which are derived from phosphoric acid (H₃PO₄). Phosphate ions are known to have a basic character as they can accept protons (H⁺) in solution, thereby increasing the pH and exhibiting basic properties.
   - The basic nature of calcium phosphate is crucial for the stability and integrity of tooth enamel. It helps neutralize acids produced by bacteria in the mouth, which can otherwise lead to tooth decay.

2. **Why Option 1 (Acidic) is Incorrect:**
   - An acidic substance would have a low pH and would donate protons (H⁺) in solution. Calcium phosphate does not exhibit these properties. Instead, it helps counteract acidity in the oral environment, which is essential for protecting teeth from acid erosion.

3. **Why Option 2 (Neutral) is Incorrect:**
   - A neutral substance would have a pH around 7, indicating no net acidic or basic properties. While calcium phosphate contributes to maintaining a balanced pH in the mouth, its inherent chemical nature is not neutral. The presence of phosphate ions gives it a basic character, distinguishing it from neutral substances.

4. **Why Option 4 (Amphoteric) is Incorrect:**
   - An amphoteric substance can act as both an acid and a base. While some compounds like aluminum hydroxide exhibit amphoteric behavior, calcium phosphate does not. Its primary role in the mouth is to act as a base, neutralizing acids rather than exhibiting dual acidic and basic properties.

In conclusion, the basic nature of calcium phosphate in tooth enamel is essential for its function in protecting teeth from acidic damage, justifying why Option 3 is the correct answer.