Question

A mole is defined as the number of atoms in an exact mass of which isotope?

Answer 1

A mole is defined as the number of atoms in a 12-gram sample of carbon-12, and it represents Avogadro's number of particles. The molar mass of a substance in g/mol is numerically equal to the mass of one atom or molecule in amu.

Step-by-step explanation:

A mole is defined as the number of atoms in an exact mass of carbon-12, the isotope of carbon that has 6 protons and 6 neutrons in its nucleus. The mole is a fundamental unit in chemistry, representing 6.02214076×10²23 particles, such as atoms, molecules, ions, or electrons, a quantity known as Avogadro's number. This specific isotope of carbon is used as the standard for defining the mole because by definition, the molar mass of carbon-12 is set to be exactly 12 grams per mole (g/mol).

Thus, when we measure one mole of a substance, we are measuring a quantity that contains the same number of particles as there are atoms in 12 grams of carbon-12. The mass of one mole of any substance will vary based on its atomic or molecular mass, but will always contain the same number of particles, equivalent to Avogadro's number. The molar mass of a substance is an intrinsic property that reflects the mass in grams of one mole of that substance, and is numerically equal to the mass of one atom or molecule of the substance expressed in atomic mass units (amu).

Answer 2

Isotope of carbon-12.

Step-by-step explanation:

The MOLE is a unit of measurement of the amount of a pure substance which contains exactly the same number of chemical units which could be (Atoms, molecules etc.) posses atoms in exactly
`12` grams of isotope of carbon-12 (i.e.,
`6.022* 10^(23)`).

So, The mole is the Notation used for an amount
`6.022* 10^(23)` as same the 12 number is used for dozen for making count of Bananas and many more.

The
`6.022* 10^(23)` is known as the fundamental constant names Avogadro's number (
`N_(A)`), It is in the honor of Italian scientist Amedeo Avogadro.