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

[Q]: If a gas in a closed area experiences increases in pressure and decreases in temperatures, the volume of the gas will be affected.
[A]: If a gas in a closed area experiences increases in pressure and decreases in temperatures, what other attribute of the gas will be affected?

[Q]: Skeletal muscles must work in pairs to move bones back and forth at a joint because they can only contract.
[A]: Skeletal muscles must work in pairs to move bones back and forth at a joint because they can only do what?

[Q]: Unburned hydrocarbons can more easily be converted to carbon dioxide and water in the presence of a catalyst.
[A]:
Unburned hydrocarbons can more easily be converted to carbon dioxide and water in the presence of a what?