Which of the following are not state functions ?
(I) q + w     (II) q
(III) w        (IV) H $$-$$ TS

Bond dissociation enthalpy of H₂, Cl₂ and HCl are 434, 242 and 431 kJ mol^$$-$$1 respectively. Enthalpy of formation of HCl is

For the gas phase reaction,

PCl_5(g)  $$\rightleftharpoons$$ PCl_3(g) + Cl_2(g)

which of the following conditions are correct ?

Consider the following reactions :
(i) H⁺_(aq) + OH^$$-$$_(aq) = H₂O_(l),  $$\Delta $$H = $$-$$ X₁ kJ mol^$$-$$1
(ii) H_2(g) + 1/2O_2(g) = H₂O_(l),   $$\Delta $$H = $$-$$ X₂ kJ mol^$$-$$1
(iii) CO_2(g) + H_2(g) = CO_(g) + H₂O_(l),  $$\Delta $$H = $$-$$ X₃ kJ mol^$$-$$1
(iv) C₂H_2(g) + 5/2O_2(g) = 2CO_2(g) + H₂O_(l),    $$\Delta $$H = +X₄ kJ mol^$$-$$1

Enthalpy of formation of H₂O_(l) is