Answer:
A
Explanation:
An atom is composed of protons, neutrons, and electrons.
The identity of an element is determined by the number of protons it has. Both atoms are carbon, so the number of protons is the same.
It is assumed that both atoms are neutral, which means that the number of electrons equal the number of protons. The number of protons is the same in both atoms, so the number of electrons in both is also the same.
Reactivity is largely determined by the number of electrons, which are the same in both, so reactivity should be the same.
The number of neutrons is the same, so there is no difference between the two atoms since the number of protons, neutrons, and electrons is the same.
