Q.Draw the TP diagram (P along the x-axis, T along the y-axis) and VT diagram (T along the x-axis, V along the y-axis) for a. Isochoric process b. Isothermal process c. Isobaric process

Step 1. Isochoric process (constant $V$): from $P\propto T$, plotting $P$ (x-axis) against $T$ (y-axis) gives a straight line through the origin. On a V-T diagram (T on x-axis, V on y-axis), since $V$ never changes, it is a horizontal line (constant $V$) -- though the question's labelling calls this the "VT diagram" with T on x and V on y, so a constant $V$ traces a straight horizontal line at that fixed $V$ value.

Step 2. Isothermal process (constant $T$): on the T-P diagram (P on x-axis, T on y-axis), since $T$ never changes, this traces a straight horizontal line at that fixed $T$ value. On the V-T diagram (T on x-axis, V on y-axis), since $T$ is fixed, this traces a straight VERTICAL line at that fixed $T$ value (V varies while T stays put).

Step 3. Isobaric process (constant $P$): on the T-P diagram (P on x-axis, T on y-axis), since $P$ never changes, this traces a straight VERTICAL line at that fixed $P$ value. On the V-T diagram (T on x-axis, V on y-axis), since $V\propto T$ at constant $P$, this traces a straight line through the origin. …

For each process, identify which variable is held fixed, and translate that into 'horizontal/vert …

• Confusing which axis is which -- the question specifically states P on the x-axis/T on the y-axis for the first diagram, and T on the x-axis/V on the y-axis for th …