GKFix MCQ Question

What is the ionization constant (Kb) of the conjugate base of HCOOH, if Ka = 1.8 × 10⁻⁴ at 298 K?

• A. 5.56 × 10⁻¹¹
• B. 1.8 × 10⁻⁴
• C. 1.0 × 10⁻¹⁴
• D. 2.7 × 10⁻¹¹