Final answer:
To arrange the gases in the mixture from highest partial pressure to lowest partial pressure, consider their relative amounts: O2, N2, CO2, He.
Step-by-step explanation:
The partial pressure of each gas in a gaseous mixture is determined by the amount of that gas present in the mixture. To arrange the gases in the mixture from highest partial pressure to lowest partial pressure, we need to consider their relative amounts. The given gases are He, O2, N2, and CO2.
First, let's look at their percentages in the atmosphere. Oxygen (O2) has the highest percentage at 20.9%, followed by nitrogen (N2) at 78.6%, carbon dioxide (CO2) at 0.04%, and helium (He) at a trace amount.
Based on their percentages, we can arrange the gases from highest to lowest partial pressure as follows: O2, N2, CO2, He.