August 2019 NY Regents Chemistry Exam
33 Which notations represent atoms that have the same number of protons but a different number of neutrons?
(1) H-3 and He-3
(2) S-32 and S-32 (3) Cl-35 and Cl-37
(4) Ga-70 and Ge-73
Solution: Atoms with the same number of protons must be atoms of the same element. We can eliminate choices 1 and 4. Different number of neutrons means different atomic mass which is written after the elements in the answer choices. We can eliminate choice 2.
Answer: 3
Ps: atoms of the same element with different number of neutrons are called isotopes.
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