Answer:
13 protons
Step-by-step explanation:
Aluminum, which has a symbol of Al, is an element in group 3 of the periodic table. It has a mass number of 27. Since the number of electrons and protons in a neutral atom are the same, a neutral/uncharged atom of aluminum contains 13 electrons, 13 protons and 14 neutrons. Note: Mass number = no. of protons + no. of electrons.
However, according to this question, an ion of aluminum has a charge of 3+, this means that an atom of aluminum has lost 3 electrons i.e. 13 electrons - 3 electrons = 10 electrons. Hence, aluminum atom with charge +3 will have 10 electrons. This doesn't change the fact that aluminum atom in a neutral state possesses 13 protons.