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

[Q]: Passage: After the film is developed, any unexposed silver bromide must be removed by a process called "fixing"; otherwise, the entire film would turn black with additional exposure to light. Although silver bromide is insoluble in water, it is soluble in a dilute solution of sodium thiosulfate (Na2S2O3; photographer's hypo) because of the formation of [Ag(S2O3)2]3 ions. Thus washing the film with thiosulfate solution dissolves unexposed silver bromide and leaves a. Answer: fixing
[A]: After the film is developed, any unexposed silver bromide must be removed by a process called what?

[Q]: Passage: The mass number is the number of protons plus the number of neutrons in an atom. For example, most atoms of helium have 2 neutrons, so their mass number is 2 + 2 = 4. This mass number means that an atom of helium has a mass of about 4 amu. Answer: protons and neutrons
[A]: What makes up the mass number of an atom?

[Q]: Passage: The temperature of the box is related to the average speed of the molecules. Use momentum principles to relate temperature to pressure. Explain conceptually, in words rather than with equations. Answer: molecules
[A]:
The temperature of the box is related to the average speed of what?