The symbol for a certain isotope of strontium is ${}^{90}_{38}$ Sr.What is the mass number of this isotope?

Name: The symbol for a certain isotope of strontium is ${}^{90}_{38}$ Sr.What is the mass number of this isotope?
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Quizplus · Accepted Answer

The mass number of an atom is the sum of its protons and neutrons. In this isotope, there are 38 protons (as indicated by the atomic number, 38) and 52 neutrons (90 - 38 = 52), so the mass number is 38 + 52 = 90. Therefore, the correct answer is choice D, 90.

The Symbol for a Certain Isotope of Strontium Is 3890{}^{90}_{38}3890​ SrWhat Is the Mass Number of This Isotope? A)38 B)52

The Symbol for a Certain Isotope of Strontium Is ${}^{90}_{38}$ SrWhat Is the Mass Number of This Isotope?
A)38
B)52