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Chemistry · EQUILIBRIUM
हिन्दीAt 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:
Correct answer · Option 3
\( 4.0 \times 10^{-9} \) and \( 8.40 \)
Explanation
Using \( K_a \times K_b = K_w \), \( K_a = \frac{1.0 \times 10^{-14}}{2.5 \times 10^{-6}} = 4.0 \times 10^{-9} \). Hence, \( pK_a = -\log(4.0 \times 10^{-9}) = 9 - \log 4 = 9 - 0.60 = 8.40 \).
