The stumper question is: a) which one of these four: Scheele, Bayen, Priestley, or Lavoisier is acknowledged as the discoverer of oxygen and b) which one gave the name oxygen to the gas that had been called "fire air" and "dephlogisticated air"?

The word oxygen is derived from two Greek words oxys and gens. Oxys means acid and gens means creator

Black's "fixed air" is now called carbon dioxide.

Rutherford's "noxious air" is now called nitrogen.

Scheele's "fire air" is now called oxygen.

Priestley's "dephlogisticated air" was the same substance as Scheele's "fire air" - it was oxygen.

Why isn't Scheele considered to be the disoverer of oxygen? The main answer is that Scheele did not publish his findings until several years after Priestley had published his.