What is the mass of calcium carbonate needed to produce 36.1 l of carbon dioxide at stp?

What is the ph of a solution with a concentration of 5.2 × 10–8 m h3o+?

Who is better, messi or cristiano, i need this for a chemistry class. asap

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.