Isotherms of carbon dioxide at various temperatures are represented in figure. Answer the following questions based on this figure.

1.  In which state will CO2 exist between the points a and b at temperature T1?

2.  At what point will CO2 start liquefying when temperature is T1?

3.  At what point will CO2 be completely liquefied when temperature T2?

4.  Will condensation take place when the temperature is T3?

5.  What portion of the isotherm at T1 represent liquid and gaseous CO2 at equilibrium?


(i) In gaseous state, CO2 will exist between the points a and b at temperature T1.
(ii) At point b, the plot becomes linear, this shows the phase transition, i.e., liquification of CO2 starts and at point c, it gets completely liquified.
(iii) Similarly, at temperature T2, g is the point at which CO2 will be completely liquified.
(iv) Condensation will not take place at T3 temperature because T3>Tc (critical temperature).
(v) Between b and c, liquid and gaseous CO2 are in equilibrium.