The number of atoms or molecules or ions present in one mole of a substance is called-

Correct option is B

The correct answer is (b) Avogadro number.
· The Avogadro number (also called Avogadro's constant) is the number of atoms, molecules, or ions present in one mole of any substance. This number is approximately 6.022 × 10²³.
· It represents the quantity of entities in a mole and is a fundamental constant used in chemistry to relate the amount of substance to the number of particles.
Information Booster:
· Normality: A measure of concentration, specifically the equivalent concentration of a solution.
· Mass number: The total number of protons and neutrons in the nucleus of an atom.
· Atomic number: The number of protons in the nucleus of an atom, which defines the element.