Which of the following statements is incorrect?
a. the only way to determine the products of a reaction is to perform the reaction.
b. all chemical reactions can be classified as one of five general types.
c. a single reactant is the identifying characteristic of a decomposition reaction.
d. complete combustion has occurred when all the carbon in the product is in the form of carbon dioxide.
(i was thinking b.)

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.