Answer:
The standard unit of mass is the kilogram.
Step-by-step explanation:
The kilogram is the basic unit of mass in the International System of Units. Among the seven basic units of the International System of Units, kilograms are the only basic unit with a prefix.
The XXVI General Conference on Weights and Measures of 2018 approved the definition of a kilogram based on fixing the numerical value of the Planck constant. The decision entered into force on May 20, 2019.