Question

Calculate the pressure of oxygen for an equilibrium system at pH = 7 and with the nitrate and ammonium concentrations equal (Note: this is the only information the question provided)

Answer 1

I am not sure but this might be the correct answer.

Let us do this way: First we will get the reaction of Nitrate with Ammonium and then we can calculate the pressure of Oxygen
So
Answer will be N2H4O3

Atmospheric pressure at sea level is 760mmHg

Oxygen constitutes of 21% of the atmosphere so the partial pressure is 21% of 760=159.6mmHg
Nitrogen constitutes of 78% of the atmosphere so the partial pressure is 78% of 760=592.8mmHg

This is my best answer. I apologize if this is wrong