Use the following terms to explain how an experiment works: hypothesis, operational definition, random selection, random assignment, control group, experimental group, independent variable, dependent variable, and confounding variable.

yes the answer is total mass in unchanged   : )

if the temperature drops and becomes cool

then the atmosphere can be freezing as the water vapor in the air is at maximum (100%) and can be severely cold

also can be snowing lightly as the moisture in the air will start to solidify

and btw this is not chemistry but