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?"

[EX Q]: Fact: insects are in the largest phylum of invertebrates.
[EX A]: What are in the largest phylum of invertebrates?

[EX Q]: Fact: fossil fuels are used for generating heat by burning.
[EX A]: What is used for generating heat by burning?

[EX Q]: Fact: Chlorine is also used to remove harmful substances from water before drinking.
[EX A]:
what is also used to remove harmful substances from water before drinking?