Paper: CSIR-NET June 2012 · Subject: Physical Chemistry · Chapter: Thermodynamics · Topic: Thermodynamics – General · Marks: 2 · Difficulty: Medium
The vapour of a pure substance, when cooled under a pressure less than its triple-piont pressure,
(a)Liquiefies
(b)Liquifies first and then solidifies
(c)Solidifies directly
(d)Remains unchanged.
Answer
Answer: C ✓ checked by 4AB · confidence high
The source book printed no answer; this one was worked out and checked — see the explanation.
Explanation
Below the triple-point pressure the liquid phase does not exist at any temperature; on cooling, the vapour deposits directly as solid (sublimation curve).