Final answer:
Statements A and B are correct. Statement A is true because in a reversible isothermal process the system absorbs heat, converting it into work during expansion, which doesn't occur in an adiabatic process. Statement B is true because a reversible adiabatic process maintains constant entropy, making it isentropic. Statements C and D are incorrect; free expansion is not reversible and heat added to a system doesn't necessarily change its internal energy.
Step-by-step explanation:
The question at hand involves understanding different thermodynamic processes and identifying the accuracy of statements related to them. Let's analyze each statement:
A. For the same volume expansion, the work done in a reversible isothermal process is more as compared to a reversible adiabatic process. This is because in a reversible isothermal process, the system is in contact with a heat source and heat is transferred into the system, which the gas converts into work. The adiabatic process does no work as a result of heat transfer because there is none; instead, the work is done at the expense of the gas's internal energy, thus less work is done for the same volume expansion with an adiabatic process.
B. A reversible adiabatic process is also known as an isentropic process. This statement is correct because 'isentropic' means 'constant entropy', and in a reversible adiabatic process, there is no heat transfer and therefore no change in entropy.
C. Free expansion is not a reversible process because it involves rapid expansion without any external work done, often against a vacuum, and thus cannot be reversed simply by reversing the process's direction.
D. If heat is given to a system, then its internal energy may change, but it is not a must. The change in internal energy also depends on the work done by or on the system, so it is possible for a system to absorb heat without changing its internal energy, such as in an isothermal process for an ideal gas.
Therefore, the correct statements are A and B.