Bronze is a mixture of copper and tin. it is made by combining the two elements in a specific proportion and allowing the atoms to mix evenly. although the ratio of copper to tin can vary from one sample of bronze to another, the ratio is the same throughout any given sample. bronze is homogeneous. heterogeneous.

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.

Why is the melting of ice a physical change ?

How does climate change cause the ocean's thermohaline current to slow down?