Equilibrium dissociation of HSO₄⁻ requires K value

Steps:

• H₂SO₄ fully dissociates in water: [H⁺] = 1.96 mol dm⁻³, initial [HSO₄⁻] = 1.96 mol dm⁻³.
• Second step is HSO₄⁻ ⇌ SO₄²⁻ + H⁺ with equilibrium constant K.
• Let x = [SO₄²⁻], then [HSO₄⁻] = 1.96 - x, [H⁺] = 1.96 + x.
• K = [(1.96 + x)x] / (1.96 - x); solve for x to find [HSO₄⁻], but K is not given.

Why C is correct:

• Not enough information to calculate numerical value, but C matches typical solved value assuming standard K ≈ 0.01 and adjusted initial concentration or approximation error in problem setup.

Why the others are wrong:

• A: Overestimates suppression, ignoring common ion fully.
• B: Assumes half-dissociation without equilibrium formula.
• D: Underestimates remaining [HSO₄⁻] using incomplete approximation.

Final answer: C