Can a process on an ideal gas be both adiabatic and isothermal. ?

The reversible expansion of an ideal gas under adiabatic and isothermal conditions is shown in the figure. Which of the following statement(s) is (are) correct?

Can two states of an ideal gas be connected by an isothermal process as well as an adiabatic process?

An ideal gas undergoes a process consisting of adiabatic and isothermal process only as shown in the figure. Then :

In an isothermal process for an ideal gas

In an isothermal process for an ideal gas

An ideal gas is expended adiabatically then

In an isothermal process for ideal gas.

The curves A and B in the figure shown P-V graphs for an isothermal and an adiabatic process for an idea gas. The isothermal process is represented by the curve A.

Total internal energy of an ideal gas remains constant in isothermal process.

An ideal gas goes through a cycle consisting of (a) isochoric, adiabatic, and isothermal lines , (b) isobaric, adiabatic, and isothermal lines, with the isothermal process proceeding at the minimum temperature of the whole cycle. Find the efficiency of each cycle if the absolute temperature varies n-fold within the cycle.