The unit of amount of substance in SI system is _____?

1. Liter (L)
2. Mole (mol)
3. Gram (g)
4. Kilogram (Kg)

The mole (symbol: mol) is the SI base unit for measuring the amount of substance. One mole contains exactly 6.02214076×10²³ elementary entities (atoms, molecules, ions, or electrons). Liter is a unit of volume, and gram and kilogram are units of mass.