Why do we heat the test tube in a glass beaker during a chemistry experiment and not directly over a flame?

Consider the following reactions. (note: (s) = solid, (l) = liquid, and (g) = gas.) mg(s) + ½o2(g) → mgo(s) + 146 kcal/mole h2(g) + ½o2(g) → h2o(g), δh = -57.82 kcal/mole what type of reaction is represented by the previous two examples?

Which statement best explains the relationship between an area is geography and the temperature of its surface water

How does the presence of oxygen affect the chemical pathways used to extract energy from glucose?