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).