What is the fundamental unit for measuring mass in the metric system?

Kilogram (kg)

It's not the SI unit of mass in the metric system however.

The correct answer is gram (g).

Explanation:

The metric system uses grams (g) as the fundamental unit of measurement of mass. This system applies the idea that units increase and decrease by a power of 10. This means that a kilogram (kg) is 1000 times heavier than a gram (g), and a gram is 1000 times heavier than a milligram (mg).

Have a nice day!