1. Concept:Thermodynamic systems are classified by their boundaries. An 'isolated' system represents the most restrictive boundary possible in physics.
2. Formula:$$\Delta m = 0 \quad \text{and} \quad Q = 0, W = 0$$
3. Solution:- An OPEN system allows both mass and energy to cross its boundaries.
- A CLOSED system allows energy (heat/work) to cross, but mass is blocked.
- An ISOLATED system is completely sealed: absolutely no mass can escape, and absolutely no energy (neither heat nor work) can cross the boundary.
4. Why other options are incorrect:Saying 'no heat transfers' only describes an adiabatic or closed system. Saying 'no mass transfers' only describes a closed system. Only 'neither heat nor mass' accurately defines total isolation.
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