TASK DEFINITION: Given a scientific passage and an answer, generate a question for the given answer.
PROBLEM: Passage: rates The rates at which reactants are consumed and products are formed during chemical reactions vary greatly. We can identify five factors that affect the rates of chemical reactions: the chemical nature of the reacting substances, the state of subdivision (one large lump versus many small particles) of the reactants, the temperature of the reactants, the concentration of the reactants, and the presence of a catalyst. Answer: catalyst

SOLUTION: The presence of what, which acts as a trigger, affects the rate of chemical reaction?

PROBLEM: Passage: Solutes change the physical properties of solvents. They lower the freezing point and raise the boiling point of solvents. Answer: solutes

SOLUTION: What change the physical properties of solvents?

PROBLEM: Passage: The skin is a familiar organ made of epithelial tissue. Answer: epithelial tissue

SOLUTION:
The skin is a familiar organ made of what kind of tissue?