Please answer the following question: John an Keith are coworkers in a chemistry lab. Yesterday, they conducted there tests, test A, test B, and test C. In test A, John kept a substance in solid state, but Keith changed the same substance from solid to liquid state. In test B, John conducted a chemical reaction in low temperature, but Keith conducted the same chemical reaction in high temperature. Finally, in test C, John kept an unstable material in room temperature, but Keith kept the same unstable material in a cool container.  In test A, whose substance would have higher temperature, John or Keith?
Answer:
Keith