The amount of substance that contains as many specified elementary particles as the number of atoms in 12 g of carbon-12 isotope is known as-

Correct option is B

The correct answer is (b) Mole.
· A mole is defined as the amount of substance that contains as many specified elementary particles (such as atoms, molecules, or ions) as there are atoms in exactly 12 grams of carbon-12. This number is known as Avogadro's number, which is approximately 6.022×1023 particles per mole. The mole is a fundamental unit in chemistry for quantifying the amount of substance.
Explanation of Other Options:
· Molecule number: This refers to the count of molecules, not the concept of a mole.
· Ion: An ion is a charged particle, not a measure of substance quantity.
· Isotope: An isotope is a variant of an element with a different number of neutrons but does not define the amount of substance.
Key Points:
· The mole is the standard unit for measuring the amount of substance in chemistry.
· It helps in quantifying and relating atomic and molecular quantities in terms of measurable amounts.