What instrument is used to find mass in science?
There is nothing like a “massometer” that really measures mass. The closest thing to a “massometer” would be a mass spectrometer. It is used primarily to identify chemical compounds in an unknown substance and to determine isotopic element ratios in compounds. The exact amount of a substance in a compound can also be determined using mass spectrometry, but that is an involved process because mass spectrometry is not usually used to quantify exact amounts.
