PLEASE HELP M Read the following chemical equation.

Fe + O2 → Fe2O3

Which of the following fractions can be used for the mole ratio to determine the mass of Fe from a known mass of Fe2O3?

four over two
three over two
two over three
two over four

The number to the right of an element's symbol (ex. c-12) identifies the of an isotope.

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.

Why is it possible for different microorganisms to extract energy not only from carbohydrates and other biological molecules but from a large variety of substances?