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

question 70

Multiple Choice

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

• A) 38
• B) 52
• C) 88
• D) 90
• E) 128

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