Answer
$\Delta S_{sys}$ is negative.
$\Delta S_{surr}$ is positive.
The reaction is spontaneous at low temperatures.
Work Step by Step
The number of moles of gas decreases from 3 to 2 and therefore entropy of the system decreases.
$\Delta S _{sys}$ is negative.
Given that $\Delta H^{\circ}_{rxn}=-483.6\,kJ$, we have
$\Delta S_{surr}=\frac{-\Delta H_{sys}}{T}\gt0$
If the reaction is spontaneous, $\Delta G\lt0$
$\implies \Delta H_{sys}-T\Delta S_{sys}\lt0$
Since both $\Delta H_{sys}$ and $\Delta S_{sys}$ are negative, $T$ should be small for $\Delta G$ to be negative.
