An element has four naturally occurring isotopes with the masses and natural abundances given here. Isotope Mass (amu) Abundance (%) 1 89.90470 52.93 2 90.90565 11.54 3 91.90504 17.65 4 93.90632 17.88 Find the atomic mass of the element. Express your answer to four significant figures and include the appropriate units.

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.

Chemical energy is a form of a. kinetic energy only. b. both potential and kinetic energy. c. neither potential nor kinetic energy. d. potential energy only. reset

Consider this initial-rate data at a certain temperature for the reaction described by