The graph below shows the radioactive decay of an isotope of strontium Based on the graph, what is the half-life of strontium?
56.2 years
14.05 years
84.3 years
28.10 years

Answer feldspar,quartz,mica and amphibole;

It is useful for historians to write narratives so that history can be passed on from their point of view.  think about a story being told in third person, then think about it again being told in first person, by someone who actually experienced the event.