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

Question

Quizplus · Accepted Answer

The mass number of an isotope is equal to the total number of protons and neutrons in its nucleus. In this case, the isotope has 38 protons (since it is strontium) and 52 neutrons (since the mass number is 90 and the atomic number is 38), so the mass number is 38+52=90. Therefore, the correct answer is D) 90.

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

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