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

Proton and neutron

Explanation:

Electrons are very light, and don't really have a significant impact on the atomic mass

- "the acute form of diverticulitis can manifest itself with one or more severe attacks of infection and inflammation.

the inflammation of diverticulitis can eventually result in a bowel obstruction, which may cause constipation, thin stools, diarrhea, abdominal swelling or bloating, and abdominal pain."