Solubility in different pressure conditions I am working on my scholarship exam practice. I believe this exam assumes high school + first year university knowledge. And I'm not quite sure what I did wrong. Could you please have a look?


  The solubility of oxygen in 1.0 L water is 28 mL at 25 °C and 1.0 atm.
  How much oxygen can be dissolved in 1.0 L of water at 25 °C and 4.0 atm?


The answer remains 28 mL but IMO I thought when pressure goes up 4 times while other factors are constant, the solubility would do that as well. Please help on where I missed and what topics I should focus on specifically.
As noted by Wikipedia, 


  "Henry's Law is a gas law that states that the amount of dissolved gas in a liquid is proportional to its partial pressure above the liquid."


So you are absolutely right. 4 times the pressure of oxygen should result in 4 times as much oxygen being dissolved. 

The answer key for the problem must be wrong.


  User Delta_G made an interesting observation/correction. The problem is asking about the volume of gas that dissolves, not the concentration of oxygen in the water. So 28 ml at 4 atm of oxygen gas contains four times as much oxygen as 28 ml at 1 atm of the gas. So in either case 28 ml of the gas phase dissolves into the water.