Answer is: concentration of SO₃² is 1.66·10⁻¹⁰ M.
Reaction
of dissociation: Ag₂SO₃(s) → 2Ag⁺(aq) + SO₃²⁻(aq).
Ksp for silver sulfite is 1.5·10⁻¹⁴.
c(Ag⁺) = 9.50·10⁻³ M; equilibrium concentration of silver cations.
Ksp = c(Ag⁺)² · c(SO₃²⁻).
c(SO₃²⁻) = Ksp ÷ c(Ag⁺)².
c(SO₃²⁻) = 1.5·10⁻¹⁴ M³ ÷ (9.50·10⁻³ M)².
c(SO₃²⁻) = 1.5·10⁻¹⁴ M³ ÷ 9.025·10⁻⁵ M².
c(SO₃²⁻) = 1.66·10⁻¹⁰ M; equilibrium concentration of sulfite anions.
