It would be an "effective secondary source document" that best describes a chart developed 20 years after a historical event, since the information as had time to "settle"--although of course this doesn't automatically mean that the chart is "effective". hope this helps :)
They used poison gas at the Battle of Ypres on April 22, 1915. It was so deadly because gas clouds were released from containers and blown by the wind towards enemy’s.
When it was formed the primary goal was to abolish slavery.
I hoped that this help you! ;-)
