A scientist designs some experiments to record how various substances change. She then reviewed her results. Which of the investigations listed below is an example of how the substance changed chemically? 1. Hydrochloric acid is stored inside plastic containers.
2. Sodium metal reacts violently and explodes with water.
3. After heating aluminum in a crucible, it began melting at 1200 degrees F
4. Grinding Copper sulfate allowed it to be dissolved much quicker.