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

[EX Q]: You call a substance that is not an acid or a base neutral.
[EX A]: What do you call a substance that is not an acid or a base?

[EX Q]: While the numerical aperture can be used to compare resolutions of various objectives, it does not indicate how far the lens could be from the specimen.
[EX A]: While the numerical aperture can be used to compare resolutions of various objectives, it does not indicate how far the lens could be from the what?

[EX Q]: The mild oxidation of thiols gives compounds called disulfides.
[EX A]:
The mild oxidation of thiols gives compounds called what?