instruction:
Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
question:
A vapor light produces visible light by electroluminescence process.
answer:
A vapor light produces visible light by what process?


question:
The male reproductive system consists of structures that produce sperm and secrete testosterone.
answer:
What does the male reproductive system consist of?


question:
The ph scale is used to succinctly communicate the acidity or basicity of a solution.
answer:

What scale is used to succinctly communicate the acidity or basicity of a solution?