Ilearning about chemical or physical properties and i don't understand whether mercury that has a density of 13 g/ml is chemical or physical or how to determine how to determine the difference

Which of the following statements is true about energy quantization at the atomic level? electrons in the outermost orbits are the most stable. electrons in all the orbits around the nucleus have the same amount of energy. electrons in the orbit closest to the nucleus have the least amount of energy. electrons absorb or release the same amount of energy independent of the energy levels.