Which of the following events is caused by Earth revolving around the sun? A. The days in a year. B. The hours in a day. C. The changes in the atmosphere of Earth. D. The position of the constellations in space.

How many grams of magnesium metal will react completely with 8.3 liters of 5.5 m hcl? show all of the work needed to solve this problem. mg (s) + 2hcl (aq) → mgcl2 (aq) + h2 (g)

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.

What is the ph of a solution that has a hydrogen ion concentration of 1.0 * 10 -9 m?