The mass of a proton is approximately equal to the mass of

(1) an alpha particle (3) a neutron

(2) an electron (4) a positron

The mass of a proton is approximately equal to the mass of a neutron.

Atoms are made of three main subatomic particles that are electrons, neutrons and protons. electrons are negatively charged and protons are positively charged and neutrons are neutral, in other words no charge.

Protons and neutrons are located in the nucleus of the atom while electrons are in energy shells that orbit around the nucleus

The mass of a proton is 1 atomic mass unit and mass of neutron is 1 atomic mass unit and electron is 1/1836th mass of an atomic mass unit

protons and neutrons have approximately similar masses and both their masses together give the mass of the atom as a whole.

answer is 3) a neutron