Answer:
The value  is  [tex]K_C = \frac{40}{600}[/tex]
Explanation:
From the question
  The equation given is Â
      NiO(s) + H2(g) ⇌ Ni(s) + H2O(g) Kc=40      (1)
      NiO(s) +CO(g) ⇌ Ni(s) +CO2(g) Kc=600     (2)
Generally the reverse of the second equation as shown below
      Ni(s) +CO2(g) ⇌  NiO(s) + CO(g)         (3)
The equilibrium constant becomes   [tex]K_c ' = \frac{1}{600}[/tex] Â
 Now  adding  1  and  3 we obtain
   NiO(s) + H2(g)+ Ni(s) +CO2(g) ⇌ Ni(s) + H2O(g)+NiO(s) + CO(g)    Â
        CO2(g) + H2(g) ⇌ CO(g) + H2O(g)
Hence the equilibrium constant for the resulting equation is mathematically evaluated as
      [tex]K_C = K_c' * K_c[/tex]
=> Â Â Â [tex]K_C = \frac{1}{600} * 40[/tex]
=> Â Â Â Â [tex]K_C = \frac{40}{600}[/tex]
   Â