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

Q: Water affects the availability of oxygen important element in aquatic environments and in flooded soils.

A: Water affects the availability of what important element in aquatic environments and in flooded soils?
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Q: Opaque is the term for matter that does not let any light pass through.

A: What is the term for matter that does not let any light pass through?
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Q: All chemical reactions involve both reactants and products.

A:
All chemical reactions involve both reactants and what else?
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