What is the approximate mass of an atom that contains 26 protons, 26 electrons and 19 neutrons?

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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