Question

Give the correct sequence of the fate of nitrogen gas in nitrogen cycle.

• A. Gaseous nitrogen fixed in the soil
• B. Nitrogen fixed in soil is converted to ammonia
• C. Ammonia is converted into nitrates
• D. Nitrates are converted back to gaseous nitrogen

Answer 1

Nitrogen fixation converts gaseous nitrogen ($N_2$) into ammonia ($N{H}_3$).
Ammonia is then converted to nitrites ($N{O}_2$), which are then converted to nitrates ($N{O}_3$). This process is called nitrification.
Finally nitrates are again converted back to gaseous nitrogen ($N_2$) by the process of denitrification to complete the nitrogen cycle.