B$.$ Working relentlessly on the previous problem for hours, Kanchou eventually drifted into sleep without even finishing what he's supposed to do $-$ drink milk. By the time he woke up$,$ the warm water he had prepared had already cooled down to $293K$ and the barometer indicated a reading of $101\mathrm{.}3$kPa.

Filled with revitalized energy from oxygenated blood running through his veins, Kanchou, eager to redeem himself from his previous setback, sets out to challenge himself once again. This time, to determine the mole fraction of oxygen in the now room temp water but exposed to dry air instead.

Before solving the problem, he recalls that the Henry's law constant for oxygen dissolved in water is $4\mathrm{.}06109Pa($mole of O$2$ Per total mole solution$)$ at $293K.$