Hello if there's any chemistry buffs out there i linked a little worksheet im struggling with, if someone could kindly give me the answers :)

When svante arrhenius first proposed his acid-base theory, he was a doctoral candidate. his professors thought his ideas were unfounded. within a decade, the arrhenius theory of acid-base was widely accepted and praised within the scientific world. arrhenius defined acids as compounds having ionizable hydrogen and bases as compounds with ionizable a) barium. b) hydronium. c) hydroxide. d) oxygen.

Which best describes how johannes kepler developed his laws of planetary motion

Stage in which a star’s outer layers have started to cool and grow outward?