How did alliances between european nations trigger a chain reaction that led to world war 1?

Alliances roped those allies into the conflict.

Explanation:

After an ally came to help a country, the opposing side also called on their allies for assistance, this is how major players such as Germany and Britain were brought into a conflict originally started between the smaller countries

i believe that the correct answer is a canadian hero.

explanation: he is celebrated as a national hero in canada for successfully thwarting a united states takeover of canada during the war of 1812.

the scientific revolution brought us a renewed understanding of humanity and our place in the universe, new scientific equipment, and new laws as a basis for future scientific discovery.