What is the largest subatomic particle

The neutron is found in the nucleus of the atom with the proton

The largest subatomic particle (by mass) is the proton

Explanation:

The largest subatomic particle (by mass) is the proton. The mass of subatomic particles is measured in atomic mass units (amu). The proton has a mass of 1.007 amu, the neutron has a mass of 1 amu, and the electron has a mass of .0005 amu.

neutron

Explanation:

Subatomic particles include electrons, the negatively charged, almost massless particles that nevertheless account for most of the size of the atom, and they include the heavier building blocks of the small but very dense nucleus of the atom, the positively charged protons and the electrically neutral neutrons.