How many components are there and what is the variance- if

Question

Consider a system composed of a solid phase of calcium carbonate (CaCO₃); a solid phase of calcium oxide (CaO); and a gaseous phase consisting of a mixture of CO₂, CaC_O3 vapor, and CaO vapor; all three constituents being present initially in arbitrary amounts. These are the substances that are present in a limekiln, where the reaction occurs.

CaCO₃ CaO + CO₂

(a) How many components are there, and what is the variance?

(b) Assuming the gaseous phase to be a mixture of ideal gases, show that

PCaOPCO₂/PCaCO₃ = K.

(c) If solid CaC0₃ is introduced into an evacuated chamber, how many components are there, and what is the variance?