system
Given the following post, respond as if you're commenting on Reddit:
human
Is there a limited number of protons, neutrons and electrons or they are created all the time?

If they are limited, can they be destroyed?
gpt
Creating a proton, neutron, or electron, requires creating the corresponding antiparticle at the same time.  Destroying them requires annihilation with an existing antiparticle.

It is easier to create electrons and positrons, because they are much less massive than protons and neutrons, so much less energy (mc^(2)) is required.  It is a common astrophysical process.