The image below shows a coherer from the 1890s, the first type of device able to receive radio waves. When a radio signal was received by the coherer, the small metal pieces inside would cling together and allow a current to pass through. The current would trigger a bell or a pen attached to a paper strip which would make a record of the signal.

The answer for #3 is c but i don't know why

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.

According to le chatelier’s principle, a system in chemical equilibrium responds to stress by shifting the equilibrium in a direction that reduces the stress. normalizes the stress. increases the stress. changes the stress.