Grams.
Probably in grams.
Metric ruler
Kilogram
The gram.
The kilogram.
Pound or ounces.
Pounds.
I would use grams.
An appropriate metric unit of mass for a pencil would be grams.
You would use kilograms (kg) to measure someone's mass in metric units.
In the SI - the current metric system - that would be the kilogram. In older metric systems, the gram has been used as the unit of mass.
A kilogram.