When she dropped a rock into a graduated cylinder of water, veronica noticed it sank to the bottom. she decided to investigate what it would do if she tossed it into a much larger amount of water. when she tossed it into a lake, the rock sank again. which statement best explained why this happened? a) the density of a substance is the same regardless of the amount. b) the lake had become less dense because of heavy rains in the past month. c) the rock was already wet from being submerged in the graduated cylinder of water. d) an object's density changes based on the amount of substance in which it is submerged.

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.

How many moles of air are there in a human lung with a volume of 2.4 l at stp? explain your answer

Astudent completes a titration by adding 12.0 milliliters of naoh(aq) of unknown concentration to 16.0 milliliters of 0.15 m hcl(aq). what is the molar concentration of the naoh(aq)? 1)5.0 m 2)0.20 m 3)0.11 m 4)1.1 m