$$\Delta $$_fG^o at 500 K for substance 'S' in liquid state and gaseous state are +100.7 kcl mol-¹ and +103 kcal mol^-1, respectively. Vapour pressure of liquid 'S' at 500 K is approximately equal to : ( R = 2 cal K^-1 mol^-1 )

Given

(i)   2Fe₂O₃(s) $$ \to $$ 4Fe(s) + 3O₂(g);

$$\Delta $$_rG^o = + 1487.0 kJ mol^-1

(ii)   2CO(g) + O₂(g) $$ \to $$ 2CO₂(g);

$$\Delta $$_rG^o = $$-$$ 514.4 kJ mol^-1

Free energy change, $$\Delta $$_rG^o for the reaction

2Fe₂O₃(s) + 6CO(g) $$ \to $$ 4Fe(s) + 6CO₂(g) will be :

For which of the following reactions, $$\Delta $$H is equal to $$\Delta $$U?

An ideal gas undergoes a cyclic process as shown in Figure.


$$\Delta $$U_BC = $$-$$5 kJ mol^-1, q_AB = $$2$$ kJ mol^-1, W_AB = $$-$$5 kJ mol^-1, W_CA = 3 kJ mol^-1. Heat absorbed by the system during process $$CA$$ is :