Which of the following elements can form double covalent bonds?

One or more substances changing into one or more substances is an example of a

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.

Can someone me with questions 12 and 13 plz.