Please help me
Which particle, protons, neutrons, or electrons, has the LEAST mass?

Electrons are much smaller in mass

Explanation:

Although similar in mass, protons are positively charged, while neutrons have no charge. Therefore, the number of neutrons in an atom contributes significantly to its mass, but not to its charge. Electrons are much smaller in mass than protons, weighing only 9.11 × 10−28 grams, or about 1/1800 of an atomic mass unit.