Chemistry · EQUILIBRIUM

At 298 K, the base dissociation constant of an organic base B is \( K_b = 2.5 \times 10^{-6} \). If the ionic product of water is \( K_w = 1.0 \times 10^{-14} \), the acid dissociation constant \( K_a \) and \( pK_a \) of its conjugate acid \( \text{BH}^+ \) are respectively:

1. A
   \( 2.5 \times 10^{-8} \) and \( 7.60 \)
2. B
   \( 4.0 \times 10^{-8} \) and \( 7.40 \)
3. C
   \( 4.0 \times 10^{-9} \) and \( 8.40 \)
4. D
   \( 2.5 \times 10^{-9} \) and \( 8.60 \)