Given a scientific passage and an answer, generate a question for the given answer.

[Q]: Passage: form of mechanical weathering that occurs as water expands when it freezes, wedging apart rock. Answer: mechanical weathering
[A]: What term describes weathering that occurs as water expands when it freezes, wedging apart rock?

[Q]: Passage: The force of gravity is called weight. Near the surface of a planet, it has magnitude and is directed perpendicular to its surface. This is different from the Gravitational Constant, and differs from planet to planet. Answer: weight
[A]: What is the force of gravity called?

[Q]: Passage: In any chemical reaction, there is no overall change in the amount of energy. Energy cannot be created or destroyed. This is the law of conservation of energy. Answer: conservation of energy
[A]:
What law states that energy cannot be created or destroyed?