Question

For which of the following processes value of $\Delta S$ is negative?

• A. $H_{2}\left(\right.g\left.\right) \rightarrow 2H\left(\right.g\left.\right)$
• B. $\mathrm{N}_2(\mathrm{~g})(1 \mathrm{~atm}) \rightarrow \mathrm{N}_2(\mathrm{~g})(8 \mathrm{~atm})$
• C. $2SO_{3}\left(\right.g\left.\right) \rightarrow 2SO_{2}\left(\right.g\left.\right)+O_{2}\left(\right.g\left.\right)$
• D. $C_{\left(\right. d i a m o n d \left.\right)} \rightarrow C_{\left(\right. g r a p h i t e \left.\right)}$

Answer 1

Answer: (B)

Processes $\text{(A)}$ and $\text{(C)}$ take place with the increase of no. of moles of gaseous species and hence the disorder or entropy increases. $\left(\right.B\left.\right)$ on increasing pressure, disorder or randomness decreases and so also the entropy $\left(\right.D\left.\right)$ is endothermic process and $\Delta S$ is positive.