You can take two liquids of different densities (how much mass is in a given volume) and pour them into a funnel. An example is oil and water. When the mixture settles, the denser liquid will be at the bottom, and drips through the funnel first. This is a separation that you can just let occur naturally.
Answer:
helium , krypton,xenon,radon, argon are noble gasses
H+= 10^-14 / [OH-1 = 3.125 * 10^-4 M
pH=-log(H+) = 3.505
Just round it down and your answer = 3.5
Humans knowingly create environmental disasters?
