Human lungs have evolved to breathe oxygen at a pressure as that in the atmosphere, 0.21 atm. If a particular heliox mixture to be carried by a scuba diver is at a pressure of 7.00 atm, what should be the partial pressure due to helium in order to maintain the pressure due to oxygen at 0.21 atm?

6.79 atm

Explanation:

Applying Dalton's law of partial pressure:

, where = total partial pressure of all the component gases in the mixture, = partial pressure of helium gas, and = partial pressure of oxygen gas.

From the illustration, = 7.00 atm and = 0.21 atm. Hence, the partial pressure due to helium is calculated such that:

=

           = 7.00 - 0.21

              = 6.79 atm

Therefore, the partial pressure due to helium in order to maintain the pressure due to oxygen at 0.21 atm would be 6.79 atm.

the answer is 0.42 is that is an option. this question provides no info