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?

Is this a scientific model? use complete sentences to explain why or why not. a graphic organizer showing the water cycle i need : ( asap i go it never mind

At 450 mm hg a gas has a volume of 760 l, what is its volume at standard pressure

Lab reagent, hypothesis test.a reference solution used as a lab reagent is purported to have a concentration of 5 mg/dl. six samples are taken from this solution and the following concentrations are recorded: (5.32, 4.88, 5.10, 4.73, 5.15, 4.75) mg/dl.these six measurements are assumed to be an srs of all possible measurements from solution.they are also assumed to have a standard deviation of 0.2, a normal distributin, and a mean concentration equal to the true concentration of the solution.carry out a significance test to determine whether these six measurements provide reliable evidence that the true concentration of the solution is actually not 5 mg/dl.