Under isothermal and reversible conditions,the term "free energy" in thermodynamics signifies

For the reaction $A \to B$,$\Delta H = 4 \, kcal \, mol^{-1}$ and $\Delta S = 10 \, cal \, K^{-1} \, mol^{-1}$. At what temperature $(K)$ will the reaction become spontaneous?

Calculate $\Delta H_f^o$ for $UBr_4$ from the $\Delta G^o$ of reaction and the $S^o$ values: $U_{(s)} + 2Br_2(\ell) \to UBr_{4(s)}$; $\Delta G^o = -788.6 \ kJ$; $S^o \ (J/K \cdot mol): U_{(s)} = 50.3, Br_2(\ell) = 152.3, UBr_{4(s)} = 242.6$.

The spontaneous nature of a reaction is impossible if

Calculate the work done (in $J$) when $4.5 \ g$ of $H_2O_2$ reacts against a pressure of $1.0 \ atm$ at $25 \ ^oC$. [$2H_2O_{2(l)} \to O_{2(g)} + 2H_2O_{(l)}$]

At a temperature of $25^\circ C$,if $\Delta H < T \Delta S$,then $\Delta G$ = ?