Why do particles with different masses have the same kinetic energy when at the same temperature?

Because Kinetic energy depends on temperature and not mass

Explanation:

Average kinetic energy is defined as the average of the kinetic energies of all the particles present in a system. It is determined by the equation:

where K.E = Kinetic energy

R= gas constant

T= temperature in kelvin

It is visible that kinetic energy is dependent on the temperature of the system and not on the mass of the system. Thus particles with different masses have the same kinetic energy when at the same temperature

c-14 is carbon-14, or radiocarbon.   it is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons.