In a phase diagram, which of the following is the term used for a substance held at a temperature and pressure where the solid, liquid, and gaseous states of a substance exist simultaneously?
A. Triple point
B. Critical temperature
C. Absolute zero
D. Critical point
A phase diagram is a graphical representation of the physical states of a substance under different conditions of temperature and pressure. A phase diagram usually has pressure on the y-axis and temperature on the x-axis. As we move along the curves of the phase diagram, we can see how the state of the substance changes from solid to liquid to gas, or vice versa.
Therefore, the Correct Answer is A.