Answer:
0.098 torr
Explanation:
We know that the partial pressure is obtained as;
partial pressure = mole fraction * total pressure
Mole fraction for Ar = 0.019
Total pressure = 0.0068 atm
partial pressure of Ar = 0.019 * 0.0068 atm = 0.0001292 atm
since 1 atm = 760 torr
0.0001292 atm = 0.0001292 atm * 760/1 atm = 0.098 torr