Question

what information cannot be identified if the number of protons for a neutral atom is known?
identity of the element
atomic number
number of neutrons
number of electrons

Explanation:

• The identity of an element is determined by its atomic number, which is equal to the number of protons. So if the number of protons is known, the identity of the element and atomic number (since atomic number = number of protons) can be identified.
• In a neutral atom, the number of electrons is equal to the number of protons, so the number of electrons can be determined from the number of protons.
• The number of neutrons is calculated as mass number - number of protons, and the mass number is not determined solely by the number of protons. So the number of neutrons cannot be identified just from the number of protons.

Answer:

number of neutrons