For which one of the following equations is $$\Delta $$H^o_react equal to $$\Delta $$H^o_f for the product ?

The densities of graphite and diamond at 298 K are 2.25 and 3.31 g cm^$$-$$3, respectively. If the standard free energy difference $$\left( {\Delta {G^o}} \right)$$ is equal to 1895 J mol^$$-$$1, the pressure at which graphite will be transformed into diamond at 298 K is

For the reaction,
C₃H_8(g) + 5O_2(g) $$ \to $$ 3CO₂(g) + 4H₂O_(l)
at constant temperature, $$\Delta $$H $$-$$ $$\Delta $$E is

2 mole of ideal gas at 27^oC temperature is expanded reversibly from 2 lit. to 20 lit. Find entropy change. (R = 2 cal/mol K)