Given a scientific passage and an answer, generate a question for the given answer.

Let me give you an example: Passage: A frameshift mutation is a deletion or insertion of one or more nucleotides that changes the reading frame of the base sequence. Deletions remove nucleotides, and insertions add nucleotides. Consider the following sequence of bases in RNA:. Answer: nucleotides.
The answer to this example can be: A frameshift mutation is a deletion or insertion of one or more of what that changes the reading frame of the base sequence?
Here is why: The science passage defines frame mutation and the main compoment here is nucleotides. Hence the generated question is apt.

OK. solve this:
Passage: What is this strange-looking object? Can you guess what it is? It's a model of a certain type of matter. Some types of matter are elements, or pure substances that cannot be broken down into simpler substances. Many other types of matter are compounds. The model above represents a compound. The compound it represents is carbon dioxide, a gas you exhale each time you breathe. Answer: carbon dioxide
Answer:
Which gas do people exhale during each breath?