Calcium phosphate is present in tooth enamel and its nature is basic.

Explanation:
1. Composition of Tooth Enamel:
Tooth enamel is the hard, outermost layer of the tooth that covers and protects the underlying dentin and pulp. It is primarily composed of hydroxyapatite, which is a crystalline form of calcium phosphate. Hydroxyapatite is a mineral that gives tooth enamel its strength and hardness.

2. Nature of Calcium Phosphate:
Calcium phosphate is an inorganic compound that contains calcium ions (Ca2+) and phosphate ions (PO43-). It is classified as a basic compound because it can accept protons (H+) and increase the concentration of hydroxide ions (OH-) in solution.

3. Acid-Base Properties:
Acidic compounds are substances that release hydrogen ions (H+) in solution, while basic compounds release hydroxide ions (OH-). Neutral compounds have an equal concentration of hydrogen ions (H+) and hydroxide ions (OH-). Amphoteric compounds can act as both acids and bases depending on the pH of the solution.

4. Tooth Enamel and pH:
Tooth enamel is constantly exposed to various acids produced by bacteria in the mouth, as well as acidic foods and drinks. The acids can demineralize the enamel, leading to tooth decay and cavities. However, tooth enamel also has the ability to remineralize itself to some extent through the uptake of minerals like calcium and phosphate ions.

5. Role of Calcium Phosphate:
Calcium phosphate plays a crucial role in maintaining the integrity and strength of tooth enamel. When the pH in the mouth becomes acidic, calcium phosphate in the enamel can release calcium ions and phosphate ions. These ions can combine with hydroxide ions (OH-) from saliva to form hydroxyapatite crystals, which remineralize the enamel and restore its hardness.

6. Conclusion:
In conclusion, calcium phosphate is present in tooth enamel and its nature is basic. It plays a vital role in maintaining the strength and integrity of tooth enamel by remineralizing it in acidic conditions.