The signs of $\Delta_r H^{\circ}$ and $\Delta_r S^{\circ}$ for a reaction to be spontaneous at all temperatures respectively are

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.

For the melting of $3 \ mol$ of ice at $0^o \text{C}$,$\Delta G = \dots \dots$

For the oxidation of ammonia at $298 \ K$,the standard enthalpy and standard entropy changes are $-382.64 \ kJ \ mol^{-1}$ and $-145.6 \ J \ K^{-1} \ mol^{-1}$ respectively. The standard Gibbs energy change for the same reaction at $298 \ K$ is $..... \ kJ \ mol^{-1}$.

$A$ spontaneous process 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 $25 \ ^oC$. [$2H_2O_{2(l)} \to O_{2(g)} + 2H_2O_{(l)}$]