How did the death of archduke franz ferdinand instigate (urge on) the collapse of peace in europe?

It was a trigger that showed that there were two competing powers in Europe: Russia and Austria-Hungary (and their allies). 

Franz Ferdinand was killed by a Serbian separatist and the Austrians wanted to see him punished. On the other hand, Russia supported Serbia is saying that Austrian demands ( to be allowed to search for the culprit inside Serbia) were too much. 

This lead to a direct conflict between the two powers (Austria and Russia) and further lead to the war. 

You ser would be coreti

It is meant that like tapestry scientific theories often need to pull out since they are not relevant and often times the whole chain of theories may be pulled out.