1. Concept:In an adiabatic process, the system is perfectly insulated so no heat escapes. Any work done ON the system directly compresses the gas and fuels an increase in internal energy.
2. Formula:$$W_{\text{on system}} = \Delta U \implies T \propto U$$
3. Solution:- When volume decreases (compression), the environment is physically doing work ON the gas.
- Because no heat can escape to the surroundings (\(Q = 0\)), all of this mechanical energy is absorbed entirely into the internal kinetic energy of the gas molecules.
- An increase in internal kinetic energy directly manifests as an increase in the absolute temperature of the gas.
4. Why other options are incorrect:Temperature decreases only during an adiabatic expansion (volume increases). It cannot remain constant unless it is an isothermal process.
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