Question

For the reaction,$A+B\rightleftharpoons C+D,K_c=9.$ If A and B are taken in equal amounts, then amount of C at equilibrium is :-
(1) 1 (2) 0.25
(3) 0.75 (4) None of these

Answer 1

The right option is 2

We have a reaction,

$A+B\leftrightharpoons C+D$

$K_c=9$

At initial,

According to the equation $1-x,1-x,x,x$

$\frac{n}{v}=\frac{1-x}{1},\frac{1-x}{1},\frac{x}{1}\frac{x}{1}$

$K_C=\frac{\left[D\right]\left[C\right]}{\left[A\right]\left[B\right]}$

$9=\frac{[1-x][1-x]}{x\times x}$

$9x^2=1-2x+x^2$

$1-2x-8x^2=0$

Therefore,

$x=0.25$

Thus the amount of the $\left[C\right]=x=0.25$