Question

A few isotherms of CO2 are shown below. Identify the correct statements (Tc is the critical temperature of CO2; T1<T2<T3<Tc):
I. At point X, CO₂ exists as liquid
II. At point Y, CO₂ exists as gas
III. At point Z, CO₂ exists as liquid

• A. I, II, III
• B. I, II only
• C. II, III only
• D. I, III only

Hint:

When analyzing phase diagrams, note that points above the phase transition curves typically represent gas, points below represent liquid, and points on the curve indicate a mixture of the two phases.

Answer 1

The Correct Option is C

Referring to the phase diagram provided:
- Point X lies on an isotherm (T1) below the critical temperature and in a phase transition region typically associated with the coexistence of liquid and vapor, not just liquid.
- Point Y is clearly in the gaseous region above the phase transition line, indicating that CO2 at point Y exists as a gas.
- Point Z is on an isotherm (T3) that is also below the critical temperature and within the liquid region of the diagram.
The correct statements based on the diagram are:
- Statement II is true: At point Y, CO2 exists as gas.
- Statement III is true: At point Z, CO2 exists as liquid.