Answer:
Actually, the correct answer is D. The system releases 75 J of heat, and its volume doubles.
Step-by-step explanation:
I took this computer-scored test, and while I was stuck on this answer for a while, I was able to get 100%. This was my thought process:
We know that molecular motion increases with an increase in temperature, because collisions increase. For that reason, for molecular motion to decrease in a system, as the question states, the system must RELEASE heat and decrease in temperature. Additionally, when a system's volume is smaller, its molecular motion increases. This is because the molecules hit the container more easily and more often. If the volume is halved then, the molecules would have MORE motion, which we aren't looking for in this question! Therefore, the volume must DOUBLE so that less molecular motion takes place. The answer is D! :)