To solve this problem, we need to analyze the reaction sequence and understand the condition provided, which is that the rate of formation of B is set to be zero.
The reaction sequence given is:
\(A \xrightarrow{K_1} B \xrightarrow{K_2} C\)
Here, \(K_1\) is the rate constant for the conversion of \(A\) to \(B\), and \(K_2\) is the rate constant for the conversion of \(B\) to \(C\).
The rate of formation of \(B\) can be expressed as:
\(\frac{d[B]}{dt} = K_1[A] - K_2[B]\)
According to the problem, the rate of formation of \(B\) is set to be zero, i.e.,
\(K_1[A] - K_2[B] = 0\)
Rearranging the terms, we get:
\(K_1[A] = K_2[B]\)
Solving for \([B]\), we find:
\([B] = \frac{K_1}{K_2}[A]\)
Thus, the concentration of \(B\) when the rate of formation is zero is given by:
\(\frac{K_1}{K_2}[A]\)
Therefore, the correct answer is \(\frac{K_1}{K_2}[A]\).
Explanation of Incorrect Options:
This reasoning helps us conclude that \(\frac{K_1}{K_2}[A]\) is the correct and logical choice based on the condition provided in the problem.
The rate of formation of B is:
\[ \frac{d[\text{B}]}{dt} = k_1[\text{A}] - k_2[\text{B}]. \]
For the rate of formation of B to be zero:
\[ \frac{d[\text{B}]}{dt} = 0. \]
Substitute:
\[ k_1[\text{A}] - k_2[\text{B}] = 0. \]
Rearrange to find [B]:
\[ k_1[\text{A}] = k_2[\text{B}] \implies [\text{B}] = \frac{k_1}{k_2}[\text{A}]. \]
Thus, the concentration of B is:
\[ [\text{B}] = \left(\frac{k_1}{k_2}\right)[\text{A}]. \]
What will be the equilibrium constant of the given reaction carried out in a \(5 \,L\) vessel and having equilibrium amounts of \(A_2\) and \(A\) as \(0.5\) mole and \(2 \times 10^{-6}\) mole respectively?
The reaction : \(A_2 \rightleftharpoons 2A\)

Cobalt chloride when dissolved in water forms pink colored complex $X$ which has octahedral geometry. This solution on treating with cone $HCl$ forms deep blue complex, $\underline{Y}$ which has a $\underline{Z}$ geometry $X, Y$ and $Z$, respectively, are
Consider the following data for the given reaction
\(2\)\(\text{HI}_{(g)}\) \(\rightarrow\) \(\text{H}_2{(g)}\)$ + $\(\text{I}_2{(g)}\)
The order of the reaction is __________.
What will be the equilibrium constant of the given reaction carried out in a \(5 \,L\) vessel and having equilibrium amounts of \(A_2\) and \(A\) as \(0.5\) mole and \(2 \times 10^{-6}\) mole respectively?
The reaction : \(A_2 \rightleftharpoons 2A\)