Which element had the longest effect on human history?

What is important to study for nios grade 12 chemistry? i have only one month left.

Read these sentences from the text. near the equator, the tropics receive the most rain on a consistent basis. as a result, the fresh water falling into the ocean decrease the salinity of the surface water in that region. [. .] . . as the salt content of sea water increases, so does its density. what can you infer about how rain affects the density of surface water near the equator?

Look at the bean data from days 4–6. use these data to explain how natural selection changed the number of dark red walking beans over time. writing part