Question

what is the relationship between a mole and avogadros number?
a mole is the mass of avogadros number of particles of a substance.
a mole is the amount of a compound that has avogadros number of carbon-12 atoms in it.
a mole contains avogadros number of particles of a substance.
a mole is the amount of any substance that has the same mass as avogadros number of carbon-12 atoms.

Explanation:

• Analyze Option A: A mole is not defined by the mass of Avogadro’s number of particles. Molar mass is related to mass, but the mole itself is about the number of particles. So A is incorrect.
• Analyze Option B: A mole is defined with respect to carbon - 12 atoms for the atomic mass unit, but a mole of a compound does not have Avogadro’s number of carbon - 12 atoms. It has Avogadro’s number of formula units (for compounds) or atoms/molecules. So B is incorrect.
• Analyze Option C: By definition, one mole of any substance contains Avogadro’s number ($6.022\times10^{23}$) of particles (atoms, molecules, ions, etc.) of that substance. This is the correct relationship.
• Analyze Option D: A mole is not defined by having the same mass as Avogadro’s number of carbon - 12 atoms. The molar mass of a substance is related to the mass of one mole, but the definition of a mole is about the number of particles. So D is incorrect.

Answer:

C. A mole contains Avogadro’s number of particles of a substance.