3. Nuclear reactions occur when the nuclei of two
different atoms collide to produce products
with different properties from the starting
substances. How is this similar to a chemical
change?
A. In a chemical change, mass can be created.
B. In a chemical change, energy can be created.
C. In a chemical change, mass can be destroyed.
D. In a chemical change, a new substance forms.

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.

As air becomes more dense, (select all that apply) o. air weighs less o. gas molecules are closer together o. air is colder o. air weighs more o. gas molecules are further apart o. air is hotter

As light moves from one material into the next, which of the following affects how much the light waves will refract, or bend? angle at which the ray strikes the medium color of the material density of the material temperature of the light wave