Final answer:
The concentrations of gases in an aqueous solution are ranked based on their solubility; oxygen is almost twice as soluble as nitrogen, while helium is less soluble due to weaker London dispersion forces. Therefore, the ranking from highest to lowest concentration is [O2] > [N2] > [He].
Step-by-step explanation:
The concentrations of gases within an aqueous solution in equilibrium with a gaseous mixture are determined by their solubility. The solubility of a gas in water is dictated by its physical properties and the interactions between water molecules and gas molecules, which is often quantified using Henry's Law constants.
For example, although oxygen (O₂) and nitrogen (N₂) share many similar physical properties, O₂ is almost twice as soluble in water as N₂ due to its paramagnetic nature, making it more polarizable. Helium (He), on the other hand, has weaker London dispersion forces due to its smaller molecular mass, resulting in a lower solubility compared to both N₂ and O₂.
Given these considerations, the relative concentrations of the gases in the aqueous solution from highest to lowest would likely be [O₂] > [N₂] > [He].