When Lead (II) Oxide, PbO, Is Allowed to React with Oxygen

Multiple Choice

When lead (II) oxide, PbO, is allowed to react with oxygen, O₂, at a temperature of 823 K and standard pressure through the reaction
PbO(s) + ½O₂(g) ∏ PbO₂(s)
The partial pressure of oxygen at equilibrium is 11.6 Pa. Determine the standard Gibbs energy of reaction at this temperature.

A) -31.0 kJ mol^-1
B) 62.0 kJ mol^-1
C) -20.8 kJ mol^-1
D) -41.4 kJ mol^-1