Question

$A\left(g\right)+B\left(g\right)\rightleftharpoons C\left(g\right)+D\left(g\right)$

For the given reaction $K_c=1$, which of the following statement is true?

• A. $\left[A\right]=\left[B\right]=\left[C\right]<\left[D\right]$
• B. $\left[A\right]\left[B\right]=\left[C\right]\left[D\right]$
• C. $\left[A\right]=\left[B\right]and\left[C\right]=\left[D\right]$
• D. $\left[A\right]\left[B\right]\left[C\right]\left[D\right]=1$

Answer 1

Answer: (B)

$\left[A\right]\left[B\right]=\left[C\right]\left[D\right]$

The equilibrium reaction is $A\left(g\right)+B\left(g\right)\rightleftharpoons C\left(g\right)+D\left(g\right),K_c=1$.

The expression for the equilibrium constant is $K_c=\frac{\left[C\right]\left[D\right]}{\left[A\right]\left[B\right]}$.
But $K_c=1$.

Hence, $\frac{\left[C\right]\left[D\right]}{\left[A\right]\left[B\right]}=1$ or $\left[A\right]\left[B\right]=\left[C\right]\left[D\right]$.

Hence, the correct option is $\text{B}$