The Nile river is the longest river in the world, followed by the Amazon river which is the second longest.
Nitrogen (78%), Oxygen (21%), Argon (0.9%), and the remaining 0.1% consists of traces of neon, krypton xenon, carbon dioxide, nitrogen oxides, and traces of others. so Nitrogen is the greatest. I hope this helps :)
Between the 1870 and 1900
It depends on the species