Which of the process described below are irrevesible?

Options

A. The increase in temperature of an iron rod by hammering it.
B. A gas in small container at a temperature `T_(1)` is brought in contact with a big reservoir at a higher temperature of the gas.
C. A quasi- static isothermal expansion of an ideal gas in cyclinder fitted with a frictionless piston.
D. An ideal gas is enclosed in a piston cyclinder arrangement with adiabatic walls. A weight `W` is added to the piston, resulting in compression of gas.

Answer

A, B, D

Explanation

(a) The increase in temperature of an iron rod by hammering it is the irrevesible process.
(b) A gas in a small container at a temperature `T_(1)` is brought in contact with a big reservoir at a higher temperature `T_(2)` which increases the temperature of the gas is also an irreversible process.
(d) An ideal gas is enclosed in a piston cyclinder arrangement with adiabatic walls. A weight `W` is added to piston resulting in compression of the gas is also an irreversible process.
In all the cases above, the original state of the system cannot be regained.