Which of the following best describes the energy involved in an exothermic chemical reaction before the reaction? select one: a. the energy was stored in chemical bonds. b. the energy was destroyed immediately during the reaction. c. the energy was created during the reaction. d. the energy was available in the environment.

Describe the difference between a. a hypothesis and a theory and b. an observation and an experiment.

Two nitro no2 groups are chemically bonded to a patch of surface. they can't move to another location on the surface, but they can rotate (see sketch at right). it turns out that the amount of rotational kinetic energy each no2 group can have is required to be a multiple of ε, where =ε×1.010−24 j. in other words, each no2 group could have ε of rotational kinetic energy, or 2ε, or 3ε, and so forth — but it cannot have just any old amount of rotational kinetic energy. suppose the total rotational kinetic energy in this system is initially known to be 32ε. then, some heat is removed from the system, and the total rotational kinetic energy falls to 18ε. calculate the change in entropy. round your answer to 3 significant digits, and be sure it has the correct unit symbol.

Which nuclide is most likely to be radioactive and synthetic 24/12 mg237/93mg195/78mg230/84mg