Final answer:
Pentane undergoes a phase change of boiling at 1 atm and 298 K.
Step-by-step explanation:
The phase change of pentane at 1 atm and 298 K is boiling, which refers to the process of a liquid becoming a gas. At this condition, pentane has enough energy to overcome the intermolecular forces and transition from a liquid to a gas state. Boiling occurs when the vapor pressure of the liquid is equal to the external pressure, which is 1 atm in this case.