Question

The standard fixed point for temperature measurements in use today is
A) melting point of ice at one atmospheric pressure
B) of pure ice and pure water in equilibrium at one atmosphere pressure
C) at which ice, water and watervapour coexist
D) none of the above

Answer 1

C) at which ice, water and water vapour coexist.
The standard fixed point for temperature measurements in use today is Triple point of water 273.16 K.