co-exist in equilibrium? (b) What is the effect of the decrease of pressure on the fusion and boiling point of Answer:
(a) The liquid and vapor phases of 
coexist at the triple point temperature and pressure of − 56.6 degrees Celsius and 5.11 atmospheres.
coexist at the triple point temperature and pressure of − 56.6 degrees Celsius and 5.11 atmospheres.
(b) When the pressure of 
is reduced, both the boiling point and the freezing point of 
decrease.
is reduced, both the boiling point and the freezing point of decrease.