Chemistry · May / June 2026 · Paper 11 · Question 15

A student investigates the rate of reaction between magnesium and excess dilute hydrochloric acid by doing three experiments. The student measures the volume of hydrogen gas produced at regular intervals. The results of the three experiments are shown. [graph: volume of hydrogen against time, curves 1, 2, 3] Which statement is correct assuming that all other conditions remain the same in each case?

1. AExperiment 1 uses the same amount of magnesium as experiment 3, but twice the concentration of hydrochloric acid.
2. BExperiment 1 uses the same amounts of reactants as experiment 2, but at a higher temperature.
3. CExperiment 2 uses twice the amount of magnesium as experiment 3, but in the presence of a catalyst.
4. DExperiment 3 uses the same amounts of reactants as experiment 2, but with powdered magnesium instead of magnesium ribbon.

As printed in the paper