Answer: Option (a) is the correct answer.
Explanation:
An atom consists of three sub-atomic particles namely protons, neutrons, and electrons.
Protons have positive charge, neutrons have no charge, and electrons are negatively charged.
Protons and neutrons reside inside the nucleus of an atom whereas electrons revolve around the nucleus of the atom. The electrons which are in the outer most shell take part in a chemical reaction and thus leads to formation of new compounds.
Hence, we can conclude that the outer electrons are the parts of an atom that are involved in chemical reactions.
