Question

1. the total number of protons and neutrons in the nucleus of an atom is its

a. average atomic mass
b. avogadro number
c. mass number

1. the atomic mass of an element listed in the periodic table is the

a. average atomic mass
b. relative atomic mass of the most abundant radioactive isotope
c. mass number of the least abundant isotope

Explanation:

For question 3, the mass number of an atom is the sum of protons and neutrons in its nucleus. For question 4, the atomic mass listed in the periodic - table is the average atomic mass which takes into account the relative abundances of all isotopes of an element.

Answer:

1. c. mass number
2. a. average atomic mass