$(30)$ Using Ellingham diagram,

a$)$ Find equilibrium partial pressure of oxygen for $Ca\frac{s}{C}aO(s)$ at $700K.$ Calculate $Kp.$

What does happen above and below equilibrium partial pressure of oxygen?

b$)$ Determine the standard molar enthalpy and entropy of formation and

$S_{298K}^0$ from the Ellingham diagram.

c$)$ Compare them $($part c$)$ with the $H^0$ and $S$ calculated in the question $2$a$.$