Question

Calcium phosphate is present in tooth enamel. Its nature is
(a) basic
(b) acidic
(c) neutral
(d) amphoteric

NCERT Class X
Science - Exemplar Problems

Chapter_Acids, Bases and Salts

Answer 1

a:basiccalcium phosphatecalcium phosphaten.1. A white amorphous powder, Ca3(PO4)2, used in ceramics, rubber, fertilizers, and plastic stabilizers and as a food supplement.2. A dibasic white crystalline powder, CaHPO4, used as an animal food, as a plastic stabilizer, and in glass and toothpaste.3. A monobasic colorless deliquescent powder, Ca(H2PO4)2, used in baking powders, as a plant food, as a plastic stabilizer, and in glass.

Answer 2

Answer: (a) basic

Explanation: Calcium phosphate $(Ca_3(PO_4)_2)$ is a basic salt, as it is a salt of weak phosphoric acid and slightly stronger base calcium hydroxide.

a) Basic  salt is formed by the combination of weak acid and a strong base. Example: $CH_3COONa$

(b) Acidic  salt is formed by the combination of strong acid and a weak base.

Example: $NH_4Cl$

(c) Neutral  salt is formed by the combination of strong acid and a strong base or weak acid and a weak base. Example: $NaCl$

(d) Amphoteric salt is one that contains an anion that can act as either an acid or a base in water. Example: $NaHCO_3$