Is it possible to prove that something is real or true of you can’t directly observe it? If no, why not? If yes, how would you do that?

How many moles of air are there in a human lung with a volume of 2.4 l at stp? explain your answer

What is the mass defect of a mole of nuclei with 1.8 x 10^15 j/mol binding energy?

This flow chart shows the amount of energy that is emitted by each type of light. ultraviolet > blue light > yellow light > red light (maximum energy) (minimum energy) in an experiment, shining which type of light on a strip of metal would be least likely to produce the photoelectric effect? ultraviolet light dim blue light bright red light bright yellow light