What is the approximate mass of an atom that has 10 electrons, 10 protons, and 9 neutrons?

Regents Chemistry Exam August 2022

32 What is the approximate mass of an atom that has 10 electrons, 10 protons, and 9 neutrons? (1) 10u

(2) 19u

(3) 20u

(4) 29u

Explanation: The mass of a an atom is equal to the sum of protons and neutrons. 10+9=19

Answer: 2