What is the purpose of using a control in scientific experiments?

Calculate the energy required to ionize a hydrogen atom to an excited state where the electron is initially in the n = 5 energy level. report your answer in kilojoules

Asample of freon gas has a volume of 2.23 liters, a pressure of 4.85 kpa, and a temperature of -1.36°c. calculate the volume at a pressure of 1.38 kpa and a temperature of 5.5°c. (show work)

Which substance can be broken down by chemical means