Question

What is the nature of calcium phosphate which is present in tooth enamel?
A.Basic
B.Acidic
C.Neutral
D.Amphoteric

Answer 1

Hint:Our tooth is made up of calcium phosphate \[C{a_3}{(P{O_4})_2}\]. It is also known as hydroxyapatite which is present in the bones also. The outer covering of the tooth is the strongest part of the body.

Step-by-step explanation:
Step 1
In the process of neutralization, the compound that is formed by the complete or partial replacement of the proton from acid with the metal or ammonium ion from a base is known as salt.
Step 2
The general properties of salt are:
They are electrovalent compounds.
They are non-volatile solids that can form crystals
Most of the salts are soluble in water and their degree of solubility in water varies with temperature.
They can exhibit acidic, basic, or neutral nature based on their reaction.
Salts formed from a strong base and weak acid dissolves in water to form an alkaline solution having a pH of more than 7.
The salts formed from a strong acid and weak base dissolves in water to form an acidic solution having a pH of less than 7.
Salts that are derived from a strong acid and strong base give a neutral solution in water.
Salts formed from a weak acid and weak base may be acidic, alkaline, or neutral depending on the nature of dissociated ions and undissociated molecules.
Some salts have a natural tendency of combining with a definite quantity of water, which is known as the water of crystallization.
Step 3
Salt hydrolysis is the phenomenon due to which salt is formed by weak acid and a strong base, or by strong acid and a weak base, dissolves in water to give an acidic or an alkaline solution.
Step 4
On the salt hydrolysis of calcium phosphate, we get calcium hydroxide which is a strong base and phosphoric acid which is a weak acid.
  \[C{a_3}{(P{O_4})_2} + 6{H_2}O\xrightarrow{{}}3Ca{(OH)_2} + 2{H_3}P{O_4}\]

Hence calcium phosphate is basic in nature. So, the correct answer for the given question is option a).

Note: The pH in our mouth is acidic, so the toothpaste is generally basic because an increase in the acidic level in the mouth increases the tooth decay as the tooth is made up of calcium phosphate which is basic in nature.