A sample of $CaCO X_{3} (s)$ is in equilibrium with $CaO (s)$ and $CO X_{2} (g)$ in a closed cylinder with a movable piston at constant temperature. Both solids remain present in every situation described. Which statements are correct?

AAdding more $CaO (s)$ does not change $p_{CO X_{2}}$
BAfter compressing the gas to half the volume and allowing equilibrium to re-establish, $p_{CO X_{2}}$ returns to its original value
C $K_{c} = [CO X_{2}]$
DDoubling the mass of $CaCO X_{3} (s)$ present doubles $p_{CO X_{2}}$

Answer: A, B, C

K_{p} = p_{CO X_{2}}

and

K_{c} = [CO X_{2}]

depend only on temperature, not on the amounts of pure solids. On compression, some

CO X_{2}

recombines with

CaO

to form

CaCO X_{3}

until

p_{CO X_{2}}

is again equal to

K_{p}

. Doubling the

CaCO X_{3}

mass changes nothing, so only statement 4 is wrong.