A solid is like the tray being shaken slowly and all the marbles moving in their positions, a liquid is like the tray being shaken and the marbles moving around it, and a gas is like the tray being shaken hard and the marbles moving vigorously around it.
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Let's look at Cassidy's analogy based upon our knowledge of the differences between solids, liquids, and gasses.
Solid = atoms are in a fixed relationship to their neighbors.
Liquid = atoms are in contact with each other, but not in a fixed relationship. They can move relative to each other.
Gas = atoms are in rapid motion and not in contact with each other.
Now let's look at the possible answers and see which corresponds to reality.
A solid is like the tray being shaken and the marbles moving around it, and a liquid is like the tray being shaken slowly and all the marbles moving in their positions.
** This one has two problems. A gas isn't even mentioned and roles of a solid vs a liquid are swapped. So this is a bad choice.
A solid is like the tray being shaken slowly and all the marbles moving in their positions, a liquid is like the tray being shaken and the marbles moving around it, and a gas is like the tray being shaken hard and the marbles moving vigorously around it.
** This sounds like a very good choice. Let's see if the remaining choices are as good or better.
A gas is like the tray being shaken slowly and all the marbles moving in their positions, and a solid is like the tray being shaken hard and the marbles moving vigorously around it.
** Two problems here as well. No mention of liquids, and the roles of solids and gasses have been swapped. Bad choice.
A liquid is like the tray being shaken hard and the marbles moving vigorously around it, and a gas is like the tray being shaken slowly and all the marbles moving in their positions.
** This one also has problems. The liquid is described the way a gas should be. And the gas is being described like a solid would be. And there's no mention of a solid. So this is a bad choice as well.
