Which element is the most abundant by mass in the Earth's atmosphere?

💡 Solution & Explanation

Nitrogen is the most abundant element and gas in Earth's atmosphere, constituting approximately 78 percent of the atmosphere by both volume and mass. Oxygen follows as the second most abundant gas at roughly 21 percent, while argon and carbon dioxide comprise the remaining trace fractions. Despite its high abundance, most organisms cannot utilize atmospheric nitrogen directly without the assistance of nitrogen-fixing bacteria.