instruction:
Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
question:
You call a substance that is not an acid or a base neutral.
answer:
What do you call a substance that is not an acid or a base?


question:
Very low density is the concentration of gas molecules in the mesosphere.
answer:
What is the concentration of gas molecules in the mesosphere?


question:
Chitin is the radula made mostly of.
answer:

What is the radula made mostly of?