Question

what is the number of protons plus the number of neutrons in the nucleus of an atom equivalent to?
average atomic mass
mass number
atomic number
number of electrons
question 12
what is the most complete list of particle(s) that are located within the nucleus of an atom?
neutrons
electrons
protons
protons and neutrons

Explanation:

1. The sum of the number of protons and neutrons in the nucleus of an atom is defined as the mass number. The average atomic mass is a weighted - average of the masses of an element's isotopes. The atomic number is the number of protons only, and the number of electrons is equal to the number of protons in a neutral atom but not related to the sum of protons and neutrons.
2. In an atom, protons and neutrons are located in the nucleus, while electrons are in the electron - cloud outside the nucleus.

Answer:

1. B. mass number
2. D. protons and neutrons