The critical point and triple point data for water are, $T_c = 374^\circ C, P_c = 22.1$ MPa, $T_T = 0.01^\circ C, P_T = 0.6$ kPa. Indicate the phase change that will occur in following cases: (i) Ice at 0.5 kPa is heated isobarically (ii) Water vapour at $400^\circ C$ is compressed isothermally
- A. (i) along AB, (ii) along CD
- B. (i) along CD, (ii) along AB
- C. (i) along OD, (ii) along PR
- D. (i) along RD, (ii) along OR
Answer: A. (i) along AB, (ii) along CD
Explanation: (i) 0.5 kPa < Triple Point Pressure, so heating ice leads to sublimation (Solid to Vapor). (ii) 400°C > Critical Temp, so compression involves no phase transition boundary (Supercritical fluid).