Grade 8 science question.. help

if a balloon was able to float to the ceiling, how could you make the balloon float in the middle (between the floor of the room?

If floats to the ceiling because it is less dense than the air around it. This is the normal buoyancy.

So, you need to decrease the buoyancy, to get neutral buoyancy. You do this by adding weights to the balloon. You keep trying until you get it right. Too much and it sinks to the floor, too little and it floats to the ceiling, but there is usually a weight amount that is "just right".

Fill the room with the same gas that's in the balloon

put in a gas which is denser than helium but less dense than air.