When dissolved in water, an arrhenius base yields(1) hydrogen ions (2) hydronium ions(3) hydroxide ions (4) oxide ions

Arrhenius bases yield hydroxide ions when in solution.  Arrhenius acids on the other hand yield hydrogen ions (which is sometimes called hydronium since the H⁺ turns to H₃O⁺ in water).

I hope this helps.  Let me know if anything is unclear.

Ibelieve it's celsius. hope this .

The correct answer should be "electrons orbit the nucleus in circular motions exactly as shown on the classic bohr model."