Which order shows the size of the inner planets from smallest to largest?

Well, they start from the smallest one, in this case Mercury , then they go to the next, Mars, followed by Venus, Earth, Neptune, Uranus, Saturn and finally end with the biggest one, Jupiter.

The proton has a positive charge while the neutron has no charge they both make up the nucleus of the atom while the elections have a negative charge and surround the nucleus of the atom. the protons and electrons are used to calculate the atom's mass whereas the neutrons don't affect the mass