Which of the following is an example of effusion?

• A. Liquid flowing through a narrow tube
• B. Water vapor condensing on a cold surface
• C. Gas escaping through a tiny hole in a balloon into a vacuum
• D. Mixing of perfume molecules with air in a room

Answer: (C)

Verified step by step guidance

1. Understand the definition of effusion: Effusion is the process by which gas particles pass through a tiny hole or narrow opening from one container to another without collisions between the particles.
2. Analyze each option in the problem to see if it matches the definition of effusion:
3. Option 1: Liquid flowing through a narrow tube involves liquid flow, not gas particles passing through a tiny hole, so it is not effusion.
4. Option 2: Water vapor condensing on a cold surface is a phase change from gas to liquid, not the passage of gas through a tiny hole, so it is not effusion.
5. Option 3: Gas escaping through a tiny hole in a balloon into a vacuum matches the definition of effusion because gas particles move through a small opening without collisions, making this the correct example of effusion.