There isn't a whole lot going on in the atmosphere of Mercury. It was unclear if Mercury actually had an atmosphere or not until '74 when Mariner 10 discovered an exosphere (an extremely thin atmosphere) around Mercury. Some of the elements that are in this exosphere are hydrogen, helium, oxygen, sodium, calcium and potassium. There is also a small trace amount of water vapor that is so hot that it will never be able to condense on the surface. Also, Mercury is so close to the sun that there is a comet like tail called a coma coming off of the surface of Mercury in the direction opposite that of the sun.
There are in fact 5 gasses you can choose from that are in Mercury's atmosphere. Oxygen, sodium, helium, potassium, and hydrogen.
helium,oxgyen,sodium
mercury has helium hydrogen and potassium
Very, very little, as Mercury's atmosphere is almost a vacuum only minute traces of gasses are found.
hydrogen and carbon dioxide
Mercury's weak gravity and close proximity to the hot sun make it easy for gasses to escape.
Molecular oxygen, sodium, hydrogen, helium, potassium, argon, nitrogen, carbon dioxide, water vapor, xenon, krypton, & neon
Mercury has no atmosphere, however, there is a trace exosphere containing hydrogen, helium, and oxygen, that gets dynamically created and destroyed.
Because the gravitational pull of the planet isn't strong enough to hold any gasses.
No - out atmosphere is made up of approximately 78% Nitrogen, 21% Oxygen and 1% other gasses.
The lack of an atmosphere, on any planet, will stop greenhouse gasses from building up, so the heat won't be trapped causing a cooler climate.
Atmosphere. It is a mixture of gasses that surrounds the earth.