Question

What is the name of the natural process that is responsible for replenishing N2 back in the atmosphere from NO3^–?

(a) Nitrification

(b) Nitrogen fixation

(c) De-nitrification

(d) Nitrate fixation

This question was addressed to me in an interview.

This is a very interesting question from P-Block Elements topic in section P-Block Elements of Chemistry – Class 12

Answer 1

The correct answer is:

(c) De-nitrification

De-nitrification is the natural process by which nitrates (NO₃⁻) are converted back into nitrogen gas (N₂) and released into the atmosphere. This process is carried out by certain bacteria in the soil under anaerobic conditions. It is an important part of the nitrogen cycle, helping to balance nitrogen in the environment.

• Nitrification is the process by which ammonia (NH₃) is oxidized to nitrates (NO₃⁻) in the soil.
• Nitrogen fixation refers to the conversion of atmospheric nitrogen (N₂) into ammonia (NH₃) by bacteria or industrial processes.
• Nitrate fixation is not a common term in the nitrogen cycle.

So, de-nitrification is the correct answer for this question.