Explanation:
Expression to calculate the value of for the given reaction is as follows.
    Â
And, it is given that
    [CO] = [tex][H_{2}][/tex] = 0.13 mol
    = 0.43 mol
Putting the given values into the above formula as follows.
     [tex]K_{c} = \frac{[CO][H_{2}]}{[H_{2}O]}[/tex]
         = [tex]\frac{0.13 \times 0.13}{0.43}[/tex]
          = 0.04
When additional amount of is added then all of has reacted.
So, new = 0 mols
    new = 0.43 + 0.13 = 0.56 mols
The reaction equation is as follows.
         [tex]C + H_{2}O \rightleftharpoons CO + H_{2}[/tex]
Initial: Â Â - Â Â 0.56 Â Â 0.13 Â Â 0 Â Â
Change: -    -x     +x     +x
Equilibm.: -   0.56 - x  0.13 + x   x
So,
      0.04 = [tex]\frac{(0.13 + x)(x)}{(0.56-x)}[/tex]
      [tex]0.0224 - 0.04x = x^{2} + 0.13x[/tex]
      [tex]x^{2} + 0.17x - 0.0224[/tex] = 0
         x = 0.087 mols
Therefore, the amount of [CO] at equilibrium is as follows.
       0.13 + 0.087
      = 0.217 mols
thus, we can conclude that the amount of CO in the flask when the system returns to equilibrium is 0.217 moles.