An atom that has 13 protons and 15 neutrons is isotope of Aluminium (answer C)
Explanation
Isotope is a form of the same element with the equal number of protons but difference number of neutrons in their nuclei.
In other words isotope has the same atomic number but different mass number.
Atomic number of a element is determined by number of protons of an element.
from the periodic table Aluminum in atomic number 13 therefore it has 13 protons therefore an atom that has 13 protons and 15 neutrons is a isotope of Aluminium.
