The dependent variable measured was

A dependent variable is what you measure in the experiment and what is affected during the experiment. The dependent variable responds to the independent variable. It is called dependent because it "depends" on the independent variable.

Explanation:

# of protons: 6

# of neutrons: 6

# of electrons: 2, 4

mass: 12.01 grams per mole of carbon atoms.

For the screenshot search up carbon atom and use a picture