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

[EX Q]: Water contains 3 atoms.
[EX A]: How many atoms does water contain?

[EX Q]: Saturated hydrocarbons hydrocarbons contain only single bonds between carbon atoms.
[EX A]: What hydrocarbons contain only single bonds between carbon atoms?

[EX Q]: Delta is a triangular feature that is formed when a river empties into a large body of still water.
[EX A]:
What triangular feature is formed when a river empties into a large body of still water?