The average atomic mass of oxygen is 15.9994 amu. the atomic masses of its three isotopes are as follows: o-16: 15.995 amu; o-17: 16.999 amu; o-18: 17.999 amu which isotope is most likely to have the greatest abundance in nature? o–16 o–17 o–18 all three isotopes may be equally abundant

Why should the scientific method be used to answer a question? a. it provides a way to test an idea without any bias. b. it provides a way to test a hypothesis. c. it provides a way to ensure all hypotheses are proven correct. d. it provides a way to quickly turn a hypothesis into a scientific theory.

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.

A50.0g sample of liquid water at 0.0 c ends up as ice at -20.0 c. how much energy is involved in this change?