Why do you think scientist can use the basic properties of matter to identify an unknown substance?

They can use the properties to test and come to some kind of conslusion about the object because in some way it's gotta correlate back to one of the different properties of matter.

3 hours because it is a decent distance.

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.