which gas is the most abundant in earth's current atmosphere
The pie chart shows the proportions of the main gases in the atmosphere. It is clear that the main gas is nitrogen. Oxygen - the gas that allows animals and plants to respire [respire: To engage in respiration - the energy-producing process inside living cells], and fuels to burn - is the next most abundant gas. These two gases are both elements and account for about 99% of the gases in the atmosphere. The remaining gases, such as carbon dioxide, water vapour and noble gases such as argon, are found in much smaller proportions.