Problem on partial pressure

Question

i) Show that the equilibrium constant K_p for the reaction

CaCo₃(s) ↔ CaO(s) +CO₂(g)

is about unity (i.e. = 1.0) at 895 °C.

ii) If two grams of calcium carbonate are placed in an evacuated container of one litre and heated to 895°C so that the reaction above is in equilibrium, what is the partial pressure of CO₂ in the chamber?

iii) What fraction of the CaCO₃ will have decomposed to CaO? Neglect the volume occupied by me solid.

iv) What would be the partial pressure of CO₂ if 0.5 gram of CaCO₃ had been placed in the chamber?