Question

why are the noble gases the least reactive elements? (1 point)
they are all radioactive
their outer most energy levels are complete with 8 electrons
they have the same number of electrons as protons
they are the last elements in each row on the periodic table

Explanation:

Noble gases are stable due to having a full outer - most energy level with 8 electrons (except helium which has 2), making them less likely to react. Radioactivity is not related to their low reactivity. Having equal numbers of electrons and protons affects charge neutrality, not reactivity. Being the last elements in a row is a position fact, not the cause of low reactivity.

Answer:

Their outer most energy levels are complete with 8 electrons.