List of top Environmental Chemistry Questions on Ozone Depletion

The Streeter-Phelp's oxygen sag equation for a river is based on a few assumptions. The correct assumption(s) is/are

The concentration of Ozone corresponding to a mixing ratio of 120 ppbv at pressure of 1 atmosphere and temperature of 25°C is ________ \(μg/m^3\) (rounded off to 1 decimal place).
Atomic weight of oxygen = 16; R= 8.314 J/K-g.mole.