Question

3. All three phases can exist in equilibrium with one another at the _____ of a substance. triple point melting point critical point boiling point

Answer 1

triple point

Step-by-step explanation:

Answer 2

Answer: triple point.

At the melting point can exist two phases in equilbrium (liquid and solid).

At the boiling point can exist two phases in equilibrium (liquid and gas).

The critical point is the limit at wich gas and liquid can coexist.

And, indeed, at the triple point can solid, liquid and gas can coexist.