What is the most abundant element found in the air and in the soil?

Nitrogen is the most abundant element found in both the air and the soil, making it critically important for various biological processes. In the atmosphere, nitrogen constitutes about 78% of the air, primarily in the form of nitrogen gas (N₂), which is inert and does not directly participate in most biological reactions.

In soil, nitrogen is essential for plant growth as it is a key component of amino acids, proteins, and nucleic acids, which are vital for the structure and function of living organisms. Plants absorb nitrogen in forms such as nitrate (NO₃⁻) and ammonium (NH₄⁺), which are vital for their growth and development. The nitrogen cycle facilitates the conversion of atmospheric nitrogen into forms usable by plants and ultimately contributes to soil fertility.

The other elements listed have their own significance, but they do not match nitrogen's abundance in the air and soil. Oxygen is present in the air but is less abundant than nitrogen and is a vital part of many organic molecules and processes. Carbon is the backbone of all organic compounds but does not make up as significant a percentage of the atmosphere. Hydrogen, while abundant in the universe, is not predominant in the air or soil relative to nitrogen. Thus, nitrogen stands out