Q3
1 markMCQSection A

The salt present in tooth enamel is :

Acids, Bases and Salts
Importance of pH in everyday life

Options

(A)Calcium phosphate
(B)Magnesium phosphate
(C)Sodium phosphate
(D)Aluminium phosphate
Official Answer

The correct option is A.

Calcium phosphatetooth enamelhardest substance

Marking Scheme

  • 1Identification of the correct salt (Calcium phosphate) (1 mark)

Hint

Recall the hardest substance in the human body that undergoes corrosion when the mouth's pH drops below 5.5.

Quick Oral Answer

The salt present in tooth enamel is calcium phosphate. It is insoluble in water but corrodes when the pH in the mouth drops below 5.5.

Analysis & Explanation

Tooth enamel is made up of calcium phosphate (specifically, calcium hydroxyapatite, a crystalline form of calcium phosphate), which is the hardest substance in the human body. It does not dissolve in water but gets corroded when the pH in the mouth falls below 5.55.5 due to acid produced by bacteria from food particles.


  • Why Option A is correct: Calcium phosphate is the actual chemical constituent of tooth enamel.
  • Why Options B, C, and D are incorrect: Magnesium phosphate, sodium phosphate, and aluminium phosphate are not present in tooth enamel and do not form the hard structural matrix of teeth.

Common Mistakes

  1. 1Students sometimes confuse calcium phosphate with calcium carbonate because calcium carbonate is found in shells and bones.

Interesting Facts

Tooth enamel is the hardest tissue in the human body, even harder than bone, and is composed of about 96% minerals, primarily calcium phosphate.

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Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2024?

This question carries 1 mark in the CBSE Class 10 Science 2024 examination.

Which chapter does this question come from in Science?

This question is from the chapter "Acids, Bases and Salts" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Importance of pH in everyday life" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2024 paper?

This is a MCQ question from Section A in the CBSE Class 10 Science 2024 paper.