Positions W and X have different surfaces. W has sharp edges, while X has smooth edges. Which experiment will show how limestone can gain different surfaces? A Cover one piece of limestone with soil, and expose another piece to wind and chemicals.
B Use chemical agents on one piece of limestone, and use physical agents on another piece.
C Compress one piece of limestone, and stretch another piece.
D Melt and cool one piece of limestone, and break up and cement another piece.

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.

answersilicon (si); oxygen (o);

sup bro, im dumb, but this is what i found xd

"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"