An ideal gas is expanded from $$(p_1, V_1, T_1)$$ to $$(p_2, V_2, T_2)$$ under different conditions. The correct statement(s) among the following is(are)

The work done on the gas is maximum when it is compressed irreversibly from $$(p_2, V_2)$$ to $$(p_1, V_1)$$ against constant pressure $$p_1$$

If the expansion is carried out freely, it is simultaneously both isothermal as well as adiabatic

The work done by the gas is less when it is expanded reversibly from $$V_1$$ to $$V_2$$ under adiabatic conditions as compared to that when expanded reversibly from $$V_1$$ to $$V_2$$ under isothermal conditions

The change in internal energy of the gas is (i) zero, if it is expanded reversibly with $$T_1 = T_2$$, and (ii) positive, if it is expanded reversibly under adiabatic conditions with $$T_1 \neq T_2$$