$1.9 xx 10^(19)$ at$"1000 K"$ and whatever pressure this was for the first reaction.
You are just supposed to write each
(By the way,
Reaction
$C Cl_4(g) + 1/2O_2(g) rightleftharpoons COCl_2(g) + Cl_2(g)$
$K_c = (["COCl"_2(g)]["Cl"_2(g)])/(["CCl"_4(g)]["O"_2(g)]^"1/2")$ (recall that the coefficients for each reaction participant are also their respective exponents.)
Reaction
$2C Cl_4(g) + O_2(g) rightleftharpoons 2COCl_2(g) + 2Cl_2(g)$ therefore having:
$K_c' = (["COCl"_2(g)]^2["Cl"_2(g)]^2)/(["CCl"_4(g)]^2["O"_2(g)])$
If we look at these ...
$[(["COCl"_2(g)]["Cl"_2(g)])/(["CCl"_4(g)]["O"_2(g)]^"1/2")]^2 = (["COCl"_2(g)]^2["Cl"_2(g)]^2)/(["CCl"_4(g)]^2["O"_2(g)])$
Therefore:
$K_c^2 = K_c'$
And so, since we have
$color(blue)(K_c') = (4.4 xx 10^9)^2 = color(blue)(1.9 xx 10^(19))$