which statement best describes a mole?\nit is 12 units of a given substance.\nit contains 6.02 x 10^23 grams…

Brief Explanations:

A mole is a unit in chemistry. One mole of any substance contains Avogadro's number ($6.02\times 10^{23}$) of particles (atoms, molecules, ions etc.). It is not 12 units of a substance. The mass of 12 carbon - 12 atoms is defined as 12 grams and is related to the definition of the atomic mass unit. Also, a mole of sodium chloride has a mass of 58.44 g/mol and not $6.02\times 10^{23}$ grams.

Answer:

It contains $6.02\times 10^{23}$ particles of a given substance.