How many protons are there in an atom of scandium-45?
A) 25
B) 66
C) 20
D) 21
E) 24

Name: How many protons are there in an atom of scandium-45? A) 25 B) 66 C) 20 D) 21 E) 24
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Question

Quizplus · Accepted Answer

Scandium has an atomic number of 21, which means it has 21 protons in its nucleus. The isotope scandium-45 has a mass number of 45, which means it has 21 protons plus 24 neutrons (45 - 21 = 24). Therefore, there are still 21 protons in an atom of scandium-45.

How Many Protons Are There in an Atom of Scandium-45