The question is incomplete, here is the complete question:
Carbon tetrachloride reacts at high temperatures with oxygen to produce two toxic gases, phosgene and chlorine.
at 1,000 K
Calculate Kc for the reaction 
<u>Answer:</u> The value of
for the final reaction is 
<u>Explanation:</u>
The given chemical equations follows:

We need to calculate the equilibrium constant for the equation, which is:

As, the final reaction is the twice of the initial equation. So, the equilibrium constant for the final reaction will be the square of the initial equilibrium constant.
The value of equilibrium constant for net reaction is:

We are given:

Putting values in above equation, we get:

Hence, the value of
for the final reaction is 
Answer:
0.758 V.
Explanation:
Hello!
In this case, case when we include the effect of concentration on an electrochemical cell, we need to consider the Nerst equation at 25 °C:

Whereas n stands for the number of moles of transferred electrons and Q the reaction quotient relating the concentration of the oxidized species over the concentration of the reduced species. In such a way, we can write the undergoing half-reactions in the cell, considering the iron's one is reversed because it has the most positive standard potential so it tends to reduction:

It means that the concentration of the oxidized species is 0.002 M (that of nickel), that of the reduced species is 0.40 M and there are two moles of transferred electrons; therefore, the generated potential turns out:

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