The equation for the reaction, BaCl2(aq) + K2CrO4(aq) → BaCrO4(s) + KCl(aq), can be written as an ionic equation. In the ionic equation, the spectator ions are

The Cl⁻ and K⁺ are spectator ions.

Explanation:

Balanced Chemical equation:

BaCl₂(aq) + K₂CrO₄(aq)   →   BaCrO₄(s) + 2KCl (aq)

Ionic equation:

Ba²⁺(aq) + 2Cl⁻(aq) + 2K⁺(aq) + CrO₄²⁻(aq) → BaCrO₄(s) + 2k⁺(aq) + 2Cl⁻ (aq)

Net ionic equation:

Ba²⁺(aq)  + CrO₄²⁻(aq)  →  BaCrO₄(s)

The Cl⁻ and K⁺ are spectator ions that's why these are not written in net ionic equation. The BaCrO₄ can not be splitted into ions because it is present in solid form.

Spectator ions:

These ions are same in both side of chemical reaction. These ions are cancel out. Their presence can not effect the equilibrium of reaction that's why these ions are omitted in net ionic equation.