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For a reaction A K1 B K2 C. If the rate of formation of B is set to be zero then the concentration of B is given by :
(4) (K1/K2)[A]
The net rate of formation of B is set to zero (steady state):
d[B]dt = K1[A] - K2[B] = 0
so K2[B] = K1[A], which gives [B] = K1K2[A].
Answer: (4)
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