What will create a insoluble salt with a potassium ion

1) The dissolution of the salt potassium sulfite:

K₂SO₃ (aq) → 2K⁺ (aq) + SO₃²⁻ (aq).

Potassium has + 1 charge because it lost one electron to accomplish stabile electron configuration of noble gas argon.

2) From dissolution reaction: n (K⁺) : n (SO₃²⁻) = 2 : 1.

n (K⁺) = 0.700 mol.

0.700 mol : n (SO₃²⁻) = 2 : 1.

n (SO₃²⁻) = 0.700 mol : 2.

n (SO₃²⁻) = 0.350 mol; amount of sulfite anions.