Question

nitrates are made by converting ammonia (nh3) to nitrite (no2) and then to nitrate (no3).
what do you predict the o2 levels in the river will be?
high - nitrate (no3) contains more oxygen atoms than ammonia (nh3), so the o2 will be high.
normal - even though oxygen atoms are added to nitrogen during the nitrogen cycle, the levels of o2 in the water
will be normal.
low - the generation of nitrates (no3) requires oxygen, so the oxygen levels will be low.

Explanation:

Step1: Analyze the nitrogen cycle and oxygen usage

The conversion of ammonia ($\text{NH}_3$) to nitrite ($\text{NO}_2^-$) and then to nitrate ($\text{NO}_3^-$) is part of the nitrogen cycle. The generation of nitrates ($\text{NO}_3^-$) requires oxygen.

Step2: Relate oxygen usage to oxygen levels

Since oxygen is consumed in the process of forming nitrates, the oxygen ($\text{O}_2$) levels in the river will be low.

Answer:

Low - The generation of nitrates ($\text{NO}_3^-$) requires oxygen, so the oxygen levels will be low.