An atom contains one proton, one electron, and one neutron. which two particles are most similar in mass?

Proton and neutron are the particles of atom with similar masses.

Explanation:

Mass of protons and neutrons are almost same and they both contribute to the mass of an atom.

Mass of electrons is very negligible as compared to protons and neutrons.

Masses of the subatomic particles:

Mass of protons = 1.007276 u

Mass of neutrons = 1.008664 u  

Mass of electrons = 0.00054858 u

Proton and neutron are the particles of atom with similar masses.

it is called acid bonding

the earth would become to overheated and everything alive on it will eventually die from overheating. plants will eventually die as well, water will evaporate, and it will be nothing but a hot planet without anything living on it.