Reactions are classified as either exothermic or endothermic. . reactions feel hot (e. g., a burning campfire), whereas reactions feel cool.

The crust of earth may a- continets and ocean floors. b-continents only. c-layers of sedimentary rocks and continents. d-all of the above

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.

How does carbon monoxide pose the greatest threat to humans? a. it can be produced by wood fires. b. it can be produced by home furnaces. c. it is produced by acid rain. d. it is produced by modern automobiles.