using the standard enthalpies of formation, what is the standard enthalpy of reaction? co(g)+h2o(g)⟶co2(g)+h2(g)

What kinds of antigens are found on the rbcs of a person with a+ blood

In the image, layer a is the topmost layer. layer c contains fossils from the precambrian era. layer b contains dinosaur fossils, and layer a contains fossils of mammals. which two statements are supported by this evidence? 1. mammals lived before the precambrian era. 2. dinosaurs and mammals existed in the precambrian era. 3. dinosaurs evolved after precambrian organisms. 4. precambrian organisms evolved after dinosaurs. 5. precambrian organisms were the first life-forms to become fossilized, according to this sample.

How many liters of 60% alcohol solution should be added to 40 liters of a 20% alcohol solution to make a 50% solution?