Hypothesis 2: If you increase the particle size of a reactant, then the reaction rate will increase because more of the reactants’ molecules will contact each other. To test the second hypothesis, you measured the reaction rate for several different

To test Hypothesis 2, change the factor it predicts will affect the reaction rate: the reactant particle size. Measure the rate at several different particle sizes and compare the results. Therefore, the correct choice is particle sizes.

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