Answer:
The answer to your question is : A. mass number is the mass of the most abundant isotope
Explanation:
A. mass number is the mass of the most abundant isotope This is the right answer because we need to consider the mass of the most abundant isotope.
B. mass number is the mass of the protons in the nucleus
. To calculate the mass number we need to consider not only the protons but also the neutrons, this option is wrong.
C. mass number is the number of protons in the nucleus
. This option is incomplete, because we need to sum the protons and neutrons to get the mass number.
D. mass number is the atomic mass of a particular isotope. Mass number is not only of a particular isotope, we need to consider the most abundant isotope, so this answer is wrong.
