Given a scientific question and its correct answer, generate supporting facts for the answer. This supporting fact can be an explanation for the answer to the given question.

Q: Question: What remains a constant of radioactive substance over time? Answer: rate of decay

A: The rate of decay of a radioactive substance is constant over time.
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Q: Question: How high or low a sound seems is associated with what property of the sound? Answer: pitch

A: How high or low a sound seems to a listener is its pitch. Pitch, in turn, depends on the frequency of sound waves.
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Q: Question: Besides the uppermost mantle, what else is the lithosphere composed of? Answer: crust

A:
The lithosphere is composed of both the crust and the uppermost mantle. The lithosphere is a brittle, rigid solid. It is easily cracked or broken.
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