Final answer:
The internal energy of a closed system can change, and an isolated system does not allow for heat transfer with the surroundings. True for a and b, but c and d are false.
Step-by-step explanation:
When analyzing the statements given, we should rely on the principles of thermodynamics concerning the internal energy of systems. The internal energy changes when heat is transferred or work is done.
- a. True: The internal energy of a system decreases when work is done on the surroundings because energy is leaving the system as work. This aligns with the concept that energy used to do work by the system reduces its own energy reserve.
- b. True: The internal energy of a system increases if heat flows from the surroundings to the system. This is consistent with the concept that heat absorbed (heat transfer) by a system raises its internal energy.
- c. False: The internal energy of a closed system is not always constant. It can change depending on heat transfer and work done. However, in an isolated system (not just closed), the internal energy would remain constant since neither heat nor matter is exchanged with the environment.
- d. False: The internal energy of an isolated system cannot be changed by heat flowing into or out of the system, as there is no heat exchange with the surroundings by definition of an isolated system.
Considering these principles, the internal energy of a system can be influenced by heat transfer or work interactions, and those interactions determine whether the internal energy will increase or decrease.