Which of the following conditions will always lead to a non-spontaneous change?

For a certain reaction, $\Delta H^0 = -345 \text{ kJ}$ and $\Delta S^0 = -123 \text{ JK}^{-1}$. At what temperature will the change over from spontaneous to non-spontaneous occur (in $\text{ K}$)?

Calculate the amount of work done during isothermal expansion of a gas from a volume of $4 \ dm^{3}$ to $6 \ dm^{3}$ against a constant external pressure of $3 \ atm$ (in $J$)?

Gibbs free energy $G$,enthalpy $H$ and entropy $S$ are interrelated as in

For the reaction $2 \ NO_{2(g)} \rightleftharpoons N_2O_{4(g)}$,when $\Delta S = -176.0 \ J \ K^{-1} \ mol^{-1}$ and $\Delta H = -57.8 \ kJ \ mol^{-1}$,the magnitude of $\Delta G$ at $298 \ K$ for the reaction is $...... \ kJ \ mol^{-1}$. (Nearest integer)

For a reaction $A + B \rightarrow$ products,$\Delta H = -84.2 \ kJ$ and $\Delta S = -200 \ J \ K^{-1}$. Calculate the highest value of temperature (in $K$) so that the reaction will proceed in the forward direction.