the most abundant gases in the atmosphere are
For the best answers, search on this site https://shorturl.im/v0RKr. Nitrogen (N2) is the most abundant gas in the Earth's atmosphere having percent volume of 78.8 compare to Oxygen 20.95 %, which falls on the second place after Nitrogen. All other gases including water vapor, CO2, helium, etc. are present in varying trace amounts a few hundredths of a percent or much less.
The next most abundant gas is (3) water vapor. Water vapor varies in concentration in the atmosphere both spatially and temporally. The highest concentrations of water vapor are found near the equator over the oceans and tropical rain forests.