PrepTest 149

Incorrect. First, the stimulus notes that this is on a spectrum, where more energy/speed increases the likelihood of an immediate split, suggesting that less energy/speed thus decreases those odds. Second, even when there's a lot of energy/speed and therefore heat, that just increases the likelihood that the atom will immediately split apart, suggesting that even with such a great amount of heat, there is still a chance that the atom won't immediately split apart.

Incorrect. This answer is contradicted by the stimulus, where it's noted that excess speed/energy still results in a resulting new atom, and thus that force must have been overcome.

Incorrect. The stimulus notes that the excess energy is what is converted to heat, and that's not directly determined by the baseline energy required to cause fusion in the first place. Making up units here, let's say one set of atoms require 10 energy to fuse, and another requires 20. The 10-energy fusion would result in a hotter atom if 20 energy is used to cause the fusion than the 20-energy fusion made with 21 energy.

Incorrect. There's no discussion of energy production, so this answer is out of scope.

Correct. Argument or Facts:
Facts

Question Type:
Must Be True

Stimulus Summary:
Fusing two atoms → Enough energy/speed to overcome forceMuch more than enough energy/speed → Created atom very hotHotter = more likely to break apart

Answer Anticipation:
Don't get lost in the science! There's a lot of complicated language here, and physics is never easy, but we don't need to understand it. We just need to look for inferences.

There are three key statements here—two conditionals ("must", "if"), and one proportional relationship ("the hotter . . . the greater"). The first statement is more background than anything.

Looking at the two conditionals, we can see that they have related terms in the necessary condition of one and the sufficient condition of the other. When terms are related but not equivalent, we have to see if the term in necessary condition guarantees the term in the sufficient condition in order to chain them. If it doesn't (if neither term guarantees the other, or if the sufficient term guarantees the necessary), we can't chain them together.

To see that last point, two examples:

(1) Rains → Cold. not Hot → Pleasant. Therefore, Rains → Pleasant. While Cold and not Hot aren't the same term, it being cold guarantees it's not hot, so we can chain these together.

(2) Clouds → not Hot. Cold → not Summer. No valid inference. Same terms, but we can't chain these statements together, because it not being hot doesn't guarantee that it's cold.

Here, there being enough energy/speed to overcome the force in question doesn't guarantee that there's much more energy than needed, so we can't chain them together. Note that had the terms been in the other positions, we could have chained them, as there being more than enough energy would guarantee that there was enough energy, just as having more than enough money to buy something guarantees you have enough money to buy it.

So with that out of the way, we're left with that proportional statement. It's related to the second conditional—more energy/speed means more heat. More heat means less stable. So the more energy in a fusion, the more likely the resulting atom is to split apart. The correct answer will likely state some version of that, and we can find that answer even if you have no idea what's going on with the science here!

Answer Explanation:
This is the inference we anticipated based on the second conditional statement and the proportional relationship established. If two atoms collide with a lot more energy than necessary, it'll be very hot. And the hotter it is, the more likely it is to immediately split apart again. So a very hot atom would be much more likely to immediately split apart, very strongly supporting this answer.

Key Takeaway:
When there are terms in two conditional statements that are related but not equivalent, there's still a possibility to chain them together to form an inference if the necessary statement guarantees the sufficient statement. This is a way that the LSAT has been upping the difficulty of conditional-logic based questions in recent years, so be sure to be aware of it!