Question

which step of the nitrogen cycle returns nitrogen gas (n₂) back to the atmosphere, completing the cycle? ammonification fixation assimilation denitrification

Explanation:

• Ammonification converts organic nitrogen to ammonia.
• Fixation converts atmospheric N₂ to usable nitrogen.
• Assimilation is when organisms take up nitrogen.
• Denitrification converts nitrate back to atmospheric N₂, closing the cycle.

Answer:

denitrification