true or False? To make a person breathe in, the volume of the chest cavity must decrease, creating a higher pressure in the thorax.

False

Explanation:

Although sometimes it feels like the opposite (where it looks like your stomach is being filled with air) you diaphragm is actually contracting and flattening itself and your chest expands. Your chest volume decreases while exhaling air due to your diaphragm and muscles in your ribs relaxing.

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.