Gibbs free energy $(G)$ is defined as

The temperature in $K$ at which $\Delta G = 0$,for a given reaction with $\Delta H = -20.5 \ kJ \ mol^{-1}$ and $\Delta S = -50.0 \ J \ K^{-1} \ mol^{-1}$ is:

The effect of temperature on the spontaneity of reactions is represented as follows:

Condition	Details
$A$. $\Delta H: +, \Delta S: -$	$T$: any $T$,Spontaneity: Non-spontaneous
$B$. $\Delta H: +, \Delta S: +$	$T$: low $T$,Spontaneity: Non-spontaneous
$C$. $\Delta H: -, \Delta S: -$	$T$: low $T$,Spontaneity: Spontaneous
$D$. $\Delta H: -, \Delta S: +$	$T$: any $T$,Spontaneity: Spontaneous

Which of the above conditions are correctly matched?

For a certain reaction,$\Delta H = -225 \ kJ \ mol^{-1}$ and $\Delta S = -150 \ J \ K^{-1} \ mol^{-1}$. Find the temperature at which $\Delta G$ is zero. (in $K$)

$A$ chemical reaction cannot occur at all if

For the reaction $CaCO_{3(s)} \to CaO_{(s)} + CO_{2(g)}$,given $\Delta H^o = 178.3 \, kJ$ and $\Delta S^o = 160 \, J \cdot K^{-1}$. At what temperature will the reaction become spontaneous?