What is for ? — Ionic Equilibrium Chemistry Question

💡 Solution & Explanation

The species $\text{PuO}_2\cdot\text{OH}^+$ acts as a conjugate base to the weak acid $\text{PuO}_2^{2+}$. The relationship between their equilibrium constants is $K_h \times K_b = K_w$. Thus, $K_b = \frac{K_w}{K_h} = \frac{10^{-14}}{2.6 \times 10^{-6}} \approx 3.84 \times 10^{-9} \approx 3.8 \times 10^{-9}$. Therefore, correct answer is C.