Please help?

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.

What is the number of moles of chemical units represented by 9.03x10^24? and how do i show work? (dumb it down )

What are the major types of a chemical compound