Question

what does the 218 in polonium-218 represent?
o the mass number
o the atomic number
o the mass defect
o the neutron number

Explanation:

In the notation of an isotope like polonium - 218, the number following the element name represents the mass number. The mass number is the sum of protons and neutrons in the nucleus of an atom. The atomic number is specific to the element and is different from this number. Mass defect is related to energy and not indicated this way. The neutron number is calculated as mass number minus atomic number and is not directly represented by this number alone.

Answer:

the mass number