Question

which of the following forms of nitrogen is shown by number 5 in the image below?

ammonia (nh₃)
atmospheric nitrogen (n₂)
nitric oxide (no)
nitrite (no₂) and nitrate (no₃)

Explanation:

In the nitrogen cycle, lightning nitrogen fixation converts atmospheric nitrogen (\(N_2\)) into nitrates (\(NO_3^-\)) and nitrites (\(NO_2^-\)). Fertilizers also contain nitrates and nitrites which are important for plant uptake. Number 5 in the image is related to these forms as it is connected to lightning nitrogen fixation and fertilizers. Ammonia (\(NH_3\)) is more related to processes like ammonification. Atmospheric nitrogen (\(N_2\)) is in the air (like number 1 in the image). Nitric oxide (NO) is not the main form here as it's more of an intermediate in some industrial or combustion - related nitrogen processes (not the main form from lightning fixation or fertilizers in the basic cycle shown).

Answer:

Nitrite (\(NO_2\)) and Nitrate (\(NO_3\))