1.
What is the mass number of an isotope of tin that has 66 neutrons and 50
protons?

Explanation:

To find the mass number of an isotope, add the number of neutrons and protons.

There are 66 neutrons and 50 protons in the this isotope of tin.

Add 66 and 50.

The mass number of this tin isotope is 116.

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