Which is the best t logical step in balancing the given equation

Define dew point. i am writing this part to be able to ask the question

A50.0 ml sample of gas at 20.0 atm of pressure is compressed to 40.0 atm of pressure at constant temperature. what is the new volume? 0.0100 ml 0.325 ml 25.0 ml 100. ml

1.) which of the following is a molecule but not a compound? a.he b.f2 c.h2o d.ch4 2.) what is a physical combination of substances? a.a compound b.a molecule c.a mixture d.an element 3.) what is a chemical combination of substances? a.a compound b.an atom c.a mixture d.an element 4.) what is the relationship between the solute and solvent in a solution? a.they form a compound b.they form a mixture c.they form molecules d.they form chemical bonds 5.) the gases in air dissolve in water. what would be one way to reduce the amount of a gas dissolved in water? a.add more water b.reduce the air pressure c.increase the air pressure d.stir the water 6.) how would you determine the solubility of a substance? a.find how well it dissolved various substances. b.find the mass and the volume of the substance. c.find the temperature at which the substance evaporated. d.find how much i was able to dissolve in a solute. 7.) the periodic table organizes all of the kinds of a.molecules. b.compounds. c.atoms. d.ions. 8.)what distinguishes two substances combined to become a compound vs. two substances combined to become a mixture? a.whether they can be easily separated b.whether they chemically bond together c.whether they both are visible d.whether they are heterogeneous 9.) the principle components of air are: n2 78% o2 21% ar 0.95% co2 0.038% this is a solution of a.molecules and atoms. b.molecules. c.compounds and molecules. d.atoms.