TASK DEFINITION: Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
PROBLEM: The frequency of a wave is the reciprocal of the period of the wave.

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

PROBLEM: Glycerol is a triol, an alcohol which contains three hydroxl functional groups.

SOLUTION: Glycerol is a triol, an alcohol which contains three what?

PROBLEM: Violet and red are two types of visible light.

SOLUTION:
Violet and red are two types of what kind of light?