Final answer:
The freezing of water in a freezer, the melting of ice in a warm room, and the gas expanding into a vacuum are spontaneous processes. Water flowing uphill without external help is a nonspontaneous process.
Step-by-step explanation:
A spontaneous process is one that occurs naturally under certain conditions, while a nonspontaneous process requires the continuous input of energy from an external source. Let's analyze each process:
a) Freezing of water at 0°C in a freezer: This is a spontaneous process because it occurs naturally when the temperature is below the freezing point of water. b) Melting of ice at 25°C in a warm room: This is a spontaneous process because the temperature is above the melting point of ice.
c) A gas expanding freely into a vacuum: This is a spontaneous process because the gas naturally fills the empty space. d) Water flowing uphill without any external help: This is a nonspontaneous process as it goes against gravity and requires external intervention to overcome the natural downhill flow.