What would you expect to happen to a balloon filled with air if it was put into a refrigerator

We know that,

when we heat air ... it expands

when we freeze air ... it decreases (shrink)

This is because when air is heated the molecules move faster and it tries to go to more places.

But, when the air is in cold place or if it is fridged ... the air molecules become slower ... as the molecules become slower ... it tends to cover less space as it is not moving fast ... So, the volume of air shrinks if it is in cold place.

So, the answer to your question is ... the balloon filled with air shrinks in volume if it was put into a refrigerator.