Which statement best describes the water molecules in a hydrate? they slide around the ions throughout the crystal lattice. they vibrate but are held in fixed positions in the crystal lattice. they have no motion because they are held in fixed positions in the crystal lattice. they vibrate randomly along the outer edges of the crystal lattice.

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

the ozone layer acts as a filter for the shorter wavelength and highly hazardous ultraviolet radiation (uvr) from the sun, protecting life on earth from its potentially harmful effects. when the sky is clear, there is an inverse relationship between stratospheric ozone and solar uvr measured at the earth's surface.