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

A electron microscope is used to see extremely small objects.
What type of microscope is used to see extremely small objects?

Unlike ammonia, oxygen cannot be liquefied at room temperature because its critical temperature is below room temperature.
Unlike ammonia, oxygen cannot be liquefied at room temperature because its what is below room temperature?

The sound in a loud classroom is an example of a form of energy.
Which of the following is an example of a form of energy?