Reread paragraph 3 what purpose does this sentence serve in the paragraph

mendeleev organized his periodic table in order of increasing atomic number in 1869.

the excerpt from the passage that best states the author's claim is: "why did people keep speaking of equality while profiting from slaves? "

when pierre lemerre the younger said in 1716 that all men were equal, slavery was reaching its crudest peak and either eastern europeans and africans were treated as objects from which powerful landlords could profit.