Question

Above critical point, the meniscus between liquid and vapour phase disappears due to:

• A. zero refractive index
• B. zero surface tension
• C. zero viscosity
• D. zero vapour pressure

Answer 1

Answer: (B)

zero surface tension

There are not many difference between liquid and gas (vapour):

1. Liquid is more dense than gas (also has greater viscosity, refraction coefficient, etc)
2. Liquid is "not compressible"
3. Liquid has surface tension and above critical temperature, gas cannot be convert into liquid and meniscus, of liquid is due to its vapour pressure and its surface tension.So above critical temperature, the meniscus between liquid and vapour phase disappears.