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

[Q]: Water can be boiled to kill giardia and most other pathogens.
[A]: Water can be boiled to kill giardia and most other what?

[Q]: The sun delivers power to the chemical factory chloroplasts.
[A]: What delivers power to the chemical factory chloroplasts?

[Q]: Expansion of a gas into a vacuum is irreversible because the external pressure is measurably less than the internal pressure of the gas, and no states of equilibrium exist.
[A]:
Expansion of a gas into a vacuum is irreversible because the external pressure is measurably less than the internal pressure of the gas, and no states of what exist?