The relation between $\Delta G$ and $\Delta H$ is

For a reaction $\Delta H = -30 \ kJ$ and $\Delta S = -45 \ J \ K^{-1}$,at what temperature does the reaction change from spontaneous to non-spontaneous (in $K$)?

Consider the graph of $Gibbs$ free energy $G$ vs. Extent of reaction. The number of statement$(s)$ from the following which are true with respect to points $(a)$,$(b)$,and $(c)$ is $.................$
$A$. Reaction is spontaneous at $(a)$ and $(b)$
$B$. Reaction is at equilibrium at point $(b)$ and non-spontaneous at point $(c)$
$C$. Reaction is spontaneous at $(a)$ and non-spontaneous at $(c)$
$D$. Reaction is non-spontaneous at $(a)$ and $(b)$

$A$ $4.50 \ g$ sample of methane occupies $12.7 \ L$ at $310 \ K$. Calculate the work done in $J$ when the gas undergoes isothermal expansion against a constant external pressure of $200 \ torr$ until the volume increases by $3.3 \ L$. (in $.99$)

Calculate the work done in Joules $(J)$ when $50 \ g$ of iron is dissolved in $HCl$ in an open beaker at $25 \ ^oC$. The atmospheric pressure is $1 \ atm$.

Which of the following pairs of a chemical reaction is certain to result in a spontaneous reaction?