Question 824268: Which of the following statements is true based on the propositions of the kinetic molecular theory? (1 point)
Select one:
a. Solids have definite shape and volume, and their particles are in a fixed non-vibrating position.
b. Liquids have indefinite shape and indefinite volume, so they can flow and be compressed.
c. Liquid substances have always had lower densities than solid substances.
d. Gases have low densities because of increased space between high-energy particles.
Answer by KMST(5328)   (Show Source):
You can put this solution on YOUR website! I vote for
d. Gases have low densities because of increased space between high-energy particles.
As a scientist, having observed the world around me for a while, I would use my own observations first, to decide what is true, and to see if a theory agrees with all of my observation.
Once I was satisfied that reality does not contradict the theory, I would draw conclusions based on the kinetic molecular theory for cases./situations where I do not have observational data.
Solids have definite shape and volume, and their particles are in a fixed in a position, but they still vibrate. That agrees with the idea that heat is kinetic energy of molecules (or ions) forming matter, and that below a certain temperature the molecules (or ions) in a substance temperatures would be rather still, making the substance have definite shape and volume, so the substance would be what we call a solid.
Liquids have indefinite shape, but well defined volume. They can flow, but they cannot be compressed much. It takes a lot of pressure to get a little reduction of volume. That is what I know from observation, and does not contradict the kinetic molecular theory.
Liquid substances do not always have lower densities than solid substances.
Ice floats in water because water is denser than ice.
Other solids float on water, and most would float on liquid mercury.
That is what I know from observation, and I do not think the kinetic molecular theory would allow to draw any conclusion about the relative densities of solids and liquids.
"Gases have low densities because of increased space between high-energy particles" sounds like a statement from the kinetic molecular theory.
It makes a lot of sense, because we know that most liquids have densities of about 1 (0.7-1.5) kg/L, while gases have densities of about 1 g/L.
I have not measured average distances between particles in gases.
I don't think I could do it directly, and I would probably be using the the kinetic molecular theory to design some experiment to measure them indirectly.
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