Concept:Avogadro's constant is a fundamental physical constant that links the microscopic world of atoms to the macroscopic world of moles and grams. It is strictly a 'number count', not a measure of mass.
Formula:$$ N_A = 6.022 \times 10^{23} \text{ entities/mol} $$
Solution:- Avogadro's constant defines the exact number of constituent particles (atoms, molecules, or ions) that are contained within exactly one mole of a given substance.
- Therefore, for any elemental substance, Avogadro's constant represents the specific number of atoms present in one mole of that element.
Why other options are incorrect:- Option A & B: Avogadro's constant is a pure number (a count), absolutely never a unit of mass.
- Option D: It is the number of atoms in 12g of specifically Carbon-12, not 12g of "any element". 12g of Hydrogen, for instance, contains 12 moles, which is 12 times Avogadro's number.
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