The term "alchemy" refers to early pseudoscientific attempts to transform common elements into more valuable elements (such as lead into gold), For one kind of atom to
become another kind of atom, which particle(s) of the atom need to be expelled or gained?
Proton
Electron
Neutron
Quantum Particles

The correct answer is option B. electron.

Explanation:

There are 3 subatomic particles:

Electrons: They carry negative charge and are present in orbits around the nucleus of an atom.Protons: They carry positive charge and are present inside the nucleus of an atomNeutrons: They does not carry any charge and are present inside the nucleus of an atom.

An atom forms an ion, when it looses or gains an electron.

When an atom looses electron, it form a positive ion known as cation.When an atom gains electron, it form a negative ion known as anion.

Hence, the correct answer is option B. electron.