Helium, oxygen, and hydrogen.
There are in fact 5 gasses you can choose from that are in Mercury's atmosphere. Oxygen, sodium, helium, potassium, and hydrogen.
mercury has helium hydrogen and potassium
helium,oxgyen,sodium
Mercury's weak gravity and close proximity to the hot sun make it easy for gasses to escape.
a very thin amount of vaporized metal
Very, very little, as Mercury's atmosphere is almost a vacuum only minute traces of gasses are found.
Mercury has no atmosphere, however, there is a trace exosphere containing hydrogen, helium, and oxygen, that gets dynamically created and destroyed.
The 3 important gasses (there are more) are:-NitrogenOxygenCarbon Dioxide
The 3 important gasses (there are more) are:-NitrogenOxygenCarbon Dioxide
Because the gravitational pull of the planet isn't strong enough to hold any gasses.
Molecular oxygen, sodium, hydrogen, helium, potassium, argon, nitrogen, carbon dioxide, water vapor, xenon, krypton, & neon
Everything except:HydrogenThe gasses on the right sideThe few liquid elements: Bromine, Gallium, and Mercury