Answer: protons and neutrons
Explanation: both of those subatomic particles are located in the nucleus and account for 99.99% of atomic mass
The subatomic particles that account for most of an atom's mass and volume are the neutrons and the protons.
Neutrons and protons are subatomic particles found in the nucleus. They are collective called nucleons.
The neutron has no charge but it contributes to the mass of the atom. The proton is positively charged and is 1840 times heavier than the electron.
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