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

[Q]: During the early paleozoic, the amount of carbon dioxide in the atmosphere was much greater compared to today.
[A]: During the early paleozoic, the amount of carbon dioxide in the atmosphere compared to today was?


[Q]: Elements are pure substances that make up all matter.
[A]: Elements are pure substances that make up what?


[Q]: Convex lenses are thicker in the middle than at the edges so they cause rays of light to converge, or meet, at a point called focus.
[A]:
Convex lenses are thicker in the middle than at the edges so they cause rays of light to converge, or meet, at a point called what?