Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Input: Consider Input: The frequency of a wave is the reciprocal of the period of the wave.

Output: The frequency of a wave is the reciprocal of what other attribute of the wave?


Input: Consider Input: Radioactive decay can give off energy and particles.

Output: Radioactive decay can give off energy and what else?


Input: Consider Input: Gases helps sound travel in waves.


Output: What helps sound travel in waves?