<span>The question is what would happen if you are given pure water in an IV. The answer is, the pure water will disrupt the osmotic balance of the body. Saline solutions are usually used in IV, this is because, there is a need to maintaint the osmotic pressure between the body cells and body fluids. Cell membranes are selectively permeable, infusing the body system with pure water will make pure water to rush into cells, dilute the contents and make the cells to swell up.</span>
Scientists developed the time scale by studying rock layers and fossils world wide.
Radioactive dating helped determine the absolute divisions in the time scale. so mass extinction help because there is more to study