Turn the given fact into a question by a simple rearrangement of words. This typically involves replacing some part of the given fact with a WH word. For example, replacing the subject of the provided fact with the word "what" can form a valid question. Don't be creative! You just need to rearrange the words to turn the fact into a question - easy! Don't just randomly remove a word from the given fact to form a question. Remember that your question must evaluate scientific understanding. Pick a word or a phrase in the given fact to be the correct answer, then make the rest of the question. You can also form a question without any WH words. For example, "A radio converts electricity into?"

Fact: fish breathe with gills.
What do aquatic animals breathe with?

Fact: Financial figures require adding.
Financial figures require what?

Fact: Rain downwind from a coal-fired power plant is likely to change the color of litmus paper from blue to red.

How will the color of litmus paper change if rain downwind of a coal-fired plant falls on it?