Question

Ice cube kept in a well-insulated thermos flask, is an example of which system?

• A. Closed system
• B. Open system
• C. Isolated system
• D. Heterogeneous system

Hint:

Think of the word "Isolated" as being "lonely." The ice in the thermos is completely cut off from the rest of the world—no heat gets in, and no water gets out.

Answer 1

The Correct Option is C

In thermodynamics, systems are classified based on their interaction with the surroundings regarding the transfer of mass and energy. 1. Types of Thermodynamic Systems:

• Open System: Both mass and energy can cross the boundary (e.g., a turbine or an open cup of coffee).

• Closed System: Only energy can cross the boundary; mass remains constant (e.g., a sealed piston-cylinder).

• Isolated System: Neither mass nor energy can cross the system boundary.

2. Analyzing the Thermos Flask: A "well-insulated thermos flask" is designed specifically to prevent any interaction with the external environment.

• Mass Transfer: Since the flask is sealed, no ice or water vapor can escape or enter.

• Energy Transfer: The vacuum insulation and silvered walls are designed to minimize heat transfer by conduction, convection, and radiation.

3. Conclusion: Because there is effectively no exchange of matter or heat between the ice cube inside the flask and the room outside, it serves as a practical example of an

Isolated system. In reality, no insulation is perfect, but for thermodynamic problems, a "well-insulated" vessel is treated as isolated.