Q. You blow at the edge of the mouth of a glass bottle first and then a plastic bottle. In which case a shriller sound will be produced ? Can you tell the reason why? Which things vibrated here to produce the sound? 

Dear Student ,
A glass bottle will create a shriller sound than the plastic bottle .Because the glass material and the air column inside it will help in producing the shriller sound .
Hence the air column inside the glass bottle will help in producing this sound .
Regards