Consider the equation below. CaCO sub 3 times s long left right arrow CaO times s plus CO sub 2 times g What is the equilibrium constant expression for the given reaction?

For an equilibrium expression, pure solids are omitted because their activities are constant. CaCO₃(s) and CaO(s) are both solids, so only gaseous CO₂ appears: Kₑq = [CO₂], which is choice C.

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