What is the SI unit for amount of substance?

The SI unit for the amount of substance is the mole. The mole is defined as the amount of substance that contains as many elementary entities, such as atoms or molecules, as there are in 0.012 kilograms of carbon-12. This unit is fundamental in chemistry because it provides a bridge between the atomic and macroscopic worlds, allowing chemists to count particles by weighing them.

Other units listed, such as gram or ounce, measure mass, while liter refers to a volume measurement. None of these units specifically represent the amount of substance in the way that the mole does, making the mole the correct answer for quantifying the number of particles in a given amount of a substance in chemical calculations and stoichiometry.