instruction:
Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
question:
Some compounds form rigid frameworks called crystals.
answer:
Some compounds form rigid frameworks called what?


question:
A student should use a balance to compare the masses of two small rocks.
answer:
Which tool should a student use to compare the masses of two small rocks?


question:
Electrochemistry is the study of the relationship between electricity and chemical reactions.
answer:

What is the study of the relationship between electricity and chemical reactions called?