June 2018 NY Regents Chemistry Exam
34 What is the approximate mass of an atom that contains 26 protons, 26 electrons and 19 neutrons?
(1) 26 u
(2) 45 u
(3) 52 u
(4) 71 u
Solution: Mass is equal to the sum of protons and neutrons. 26 protons + 19 neutrons = 45 atomic mass units.
Answer: 2
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