Which SI base unit measures amount of substance?

Which SI base unit measures amount of substance?

• A. Gram (g)
• B. Liters (L)
• C. Candela (cd)
• D. Mole (mol)

Answer: (D)

Amount of substance is measured in moles, the unit that counts how many elementary entities are present. A mole represents exactly 6.02214076×10^23 atoms, molecules, ions, or other particles, linking the microscopic world to macroscopic measurements. This definition makes the mole the SI base unit for quantity of substance, focusing on how many particles exist rather than how heavy they are. In 2019 the mole was redefined to fix Avogadro’s constant, so one mole corresponds to that exact number of particles. The other options don’t quantify amount of substance: a gram measures mass, a liter measures volume, and a candela measures luminous intensity.

Amount of substance is measured in moles, the unit that counts how many elementary entities are present. A mole represents exactly 6.02214076×10^23 atoms, molecules, ions, or other particles, linking the microscopic world to macroscopic measurements. This definition makes the mole the SI base unit for quantity of substance, focusing on how many particles exist rather than how heavy they are. In 2019 the mole was redefined to fix Avogadro’s constant, so one mole corresponds to that exact number of particles.

The other options don’t quantify amount of substance: a gram measures mass, a liter measures volume, and a candela measures luminous intensity.