Answer
a. The gas moves out into the surrounding air.
b. No.
c. Breaking something; Creating a homogeneous mixture.
Work Step by Step
a. The chlorine gas emerges and is found in the room as well as in the bottle.
b. The reverse process, where all the chlorine spontaneously jumps back into in the bottle, violates the second law of thermodynamics and would never occur spontaneously.
c. Breaking a fragile vase with a hammer is another example of an irreversible process, as is stirring chocolate syrup into a glass of water.