Answer: True.
Step-by-step explanation:
Since the gases are given momentum as they are ejected by the rocket engine, a rocket moves in space. Consider the rocket in space as it rests. The device does not have any momentum. Next, it ignites the engine. As the exhaust gases go in one direction, to keep the overall momentum of the device steady, the rocket goes in the other. This shift in momentum of the gases gives the rocket the "push" to move forward. This push is what we call the thrust of the rocket.