A cyclic process is shown in the p-T diagram. Which of the curves...

- Given diagram: P-T graph. - Using ideal gas law: (P V=n R T \Rightarrow V=$\frac{n R T}{P}$. So in a $P-T$ graph we can infer how $V$ behaves. Step analysis of cycle ($\mathrm{A} \rightarrow \mathrm{B} \rightarrow \mathrm{C} \rightarrow \mathrm{A}$ : - A ($\rightarrow \mathrm{B}: Both$P$$and$T$increase proportionally (straight line through origin). (\Rightarrow V=\frac{n R T}{P}=\text{ constant. }$ So ($\mathrm{A}$ \rightarrow $\mathrm{B}$ is an isochoric process in $P-V$. - ($\mathrm{B}$ \rightarrow $\mathrm{C}$: T) constant, $P$ decreases. (\Rightarrow) Isothermal expansion$in$P-V$. - (\mathrm{C} \rightarrow\mathrm{A}: P) constant,$T$decreases. (\Rightarrow) Isochoric process in$P-V$. So the cycle consists of: - Isochoric line, - Isothermal curve, - Isochoric line. This matches diagram (2).