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

[EX Q]: A volcano chain is formed by subduction of oceanic crust beneath a continental or oceanic plate.
[EX A]: What kind of chain is formed by subduction of oceanic crust beneath a continental or oceanic plate?

[EX Q]: Monatomic ions form when a single atom gains or loses electrons.
[EX A]: What form when a single atom gains or loses electrons?

[EX Q]: There are three chambers in a reptiles heart.
[EX A]:
How many chambers are in a reptiles heart?