Cambridge Secondary (7-9). Stage 8. Science. Learner's Book - Unit 8: Chemical reactions - Question 67

Some other metals react less vigorously with water – for example, calcium and magnesium. In the experiment shown in the diagram, a piece of calcium has been placed at the bottom of a beaker and covered with water. A filter funnel has been placed upside down over the metal. The gas given off is collected in a test tube by the displacement of water.



How could you tell if calcium or magnesium is more reactive?