How do protons distinguish between atoms

the reaction mixture contains some ammonia, plus a lot of unreacted nitrogen and hydrogen. the mixture is cooled and compressed, causing the ammonia gas to condense into a liquid. the liquefied ammonia is separated and removed. the unreacted nitrogen and hydrogen are then recycled back into the reactor .

it’s previous models   because when i picked that son of a gun’s answer it was wrong look for previous models because they might make it a different letter