When a neutral hydrogen atom loses an electron, a positively-charged particle should remain.
Explanation:
Carbon-12 atoms have stable nuclei because of the 1:1 ratio of protons and neutrons.
Carbon-14 atoms have nuclei which are unstable. C-14 atoms will undergo alpha decay and produce atoms of N-14. Carbon-14 dating can be used to determine the age of artifacts which are not more than 50,000 years old.
The mass of electrons, protons, and neutrons:
electrons 9.10938291*10^-31 kg
protons 1.67262178*10^-27 kg
neutrons 1.6749*10^-27 kg
the mass of electrons is way smaller than both, the mass of protons and neutrons
therefore, 1) the mass of 2 electrons is the smallest