June 2017 NY Regents Chemistry Exam
4 Which particle has the least mass?
(1) a proton
(2) an electron
(3) a helium atom
(4) a hydrogen atom
Solution: An electron is very small and has a very small amount of mass compared to the mass of a proton. Helium atom has 2 protons (atomic number) and a hydrogen atom has 1 proton.
Answer: 2
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