Question

witch unit is used to measure mass in the metric system

Answer 1

the gram (g)
a nickel weighs 5 grams, and a raisin weighs approximately 1 gram.
There is also the kilogram(kg), or 1000 grams

Answer 2

Gram [g]

An uncommonly used unit of mass:

Centi-gram [cg]

Kilo-gram [kg]

Hope this helped ;)