What is the Major Reservoir of Stable Nitrogen

Question

What is the major reservoir of stable nitrogen?
A) N₂
B) NO
C) NO₃⁻
D) NH₄

Accepted Answer

The major reservoir of stable nitrogen is N₂ gas, which makes up approximately 78% of the Earth's atmosphere. Nitrogen in other forms such as NO, NO₃⁻, and NH₄⁺ are all relatively unstable and can be easily converted to other nitrogen compounds through various biogeochemical processes. Therefore, N₂ is the most stable and abundant form of nitrogen on Earth.