instruction:
Given a scientific passage and an answer, generate a question for the given answer.
question:
Passage: Solutes change the physical properties of solvents. They lower the freezing point and raise the boiling point of solvents. Answer: solutes
answer:
What change the physical properties of solvents?

question:
Passage: Intensity is defined to be the power per unit area carried by a wave. Power is the rate at which energy is transferred by the wave. In equation form, intensity I is. Answer: wave
answer:
Intensity is defined to be the power per unit area carried by a what?

question:
Passage: A: All chemical equations must be balanced. This means that there must be the same number of each type of atom on both sides of the arrow. That's because mass is always conserved in chemical reactions. Count the number of hydrogen and oxygen atoms on each side of the arrow. There are two hydrogen atoms in both reactants and products. There are two oxygen atoms in the reactants but only one in the product. Therefore, equation 1 is not balanced. Answer: mass
answer:
What is always conserved in chemical reactions?