Q75 · CSIR-NET Chemistry, June 2017
Paper: CSIR-NET June 2017 · Subject: Physical Chemistry · Chapter: Thermodynamics · Topic: Phase Equilibria · Marks: 2 · Difficulty: Medium
A one-component system with the associated phase diagram (see the figure) is not possible because 
(a)OB has a negative slops
(b)OC has a positive slope
(c)Both OB and OC are linear
(d)$\mathrm{OB}, \mathrm{OC}$ and OD cannot all coexist, given OA
Answer
Answer: D ✓ checked by 4AB · confidence high
Explanation
With one component only three phases can meet at a point; four boundaries OA, OB, OC and OD meeting at O would need four phases in equilibrium (F = −1), which the phase rule forbids.
Study loop for Thermodynamics