When Zac releases the air from a balloon, it will expand to fill the room. It will not expand in the sense that molecules will be big but the molecules will be more spread out into the room and more air molecules will be present to fill the room.
Step-by-step explanation:
As the air inside the balloon is burned its volume rises, inflating the balloon more completely. Having a greater volume makes it less dense than the neighboring air so it glides upward
When we open the balloon, the air is delivered to the air inside the balloon is at the corresponding pressure as the air outside the balloon. When this occurs, the air emerging from the balloon results in a force in the reverse direction sending the actual balloon in the opposite direction. And it expands to fill a room.