Q: What do fission reactors use to slow down the neutrons? Choices: - inertia - brake - control - moderator A:
moderator

Q: A wall of rocks or concrete that juts out into the ocean perpendicular to the shore is called? Choices: - shield - rib - fault - groin A:
groin

Q: What property of warm air causes it to rise above cold air? Choices: - greater pressure - greater density - higher temperature - lower density A:
lower density