At would be the saturation concentration (mole/l) of oxygen (o2) in a river in winter when the air temperature is 0°c if the henry's law constant at this temperature is 2.28 * 10-3 mole/latm

the concentration of oxygen will be

concentration = K X partial pressure

K = Henry'a law constant = 2.28 * 10-3 mole/latm

Partial pressure of O2 = 0.21 (in atmosphere)

Concentration = 2.28 * 10-3 mole/latm X 0.21 = 4.788 X 10^-4 mol / L