Absolute Entropy and Entropy Change Practice Test

Solid ammonium chloride is heated in a closed container and decomposes according to $\text{NH}_4\text{Cl}(s) \rightarrow \text{NH}_3(g) + \text{HCl}(g)$. After heating, only gases are present. Which statement best describes the sign of $\Delta S$ for the system?

In a sealed syringe, a fixed amount of Ar(g) is compressed by pushing the plunger inward at constant temperature, changing from a larger volume to a smaller volume. Which statement best describes the sign of $\Delta S$ for the gas in the syringe?