Consider the total ionic equation below.
2h⁺+ cro²⁻₄+ba²⁺+2oh⁻--> ba²⁺+cro²⁻₄+2h2o
what are the spectator ions in this equation?
h+ and oh-
h+ and ba2+
cro²⁻₄ and oh⁻
cro²⁻₄ and ba²⁺

The spectator ions in this equation are :

CrO²⁻₄ and Ba²⁺

Explanation:

Spectator ions : These are the ions which are present in the solution but do not take part in chemical reaction.They are present as such in  both reactant as well as product .

In this reaction,

1.H+ and OH- are combined and converted into water (H2O) : Changed to H2O

So , H+ and OH- are not Spectator ions

2.CrO²⁻₄ and Ba²⁺ are unchanged . Present as such in product and reactants

CrO²⁻₄ and Ba²⁺are Spectator ions

the old alchemists made significant contributions to science even though there starting premises were off a bit. their conclusions after failure would steer them into better directions for investigation. science is no more than close observation and the initial mistakes result in rethinking and retrying experiments.