The statement below is followed by four options. Each option is related to the item in the statement, but only one is always true. Select the option that always holds and makes the statement true.
"An atom always has ______."
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Protons
The answer must hold for every atom, without exception. An option that is present in most cases but can be missing in even one case is not always true.
Option (1) Neutrons — the ordinary hydrogen atom (protium) has one proton and no neutron, so not every atom has neutrons.
Option (2) Protons — the number of protons is the atomic number, and every element has an atomic number of at least 1; an atom with no proton does not exist, so this is always true.
Option (3) An overall positive charge — an atom has equal numbers of protons and electrons, so as a whole it is neutral, not positive.
Option (4) Two electrons — a hydrogen atom has only one electron, and most atoms have many more than two.