A ringing alarm clock is put under a glass jar. The air is slowly removed from the space around it. What will happen as the air is removed, where the clock slowly become less visible until you can only hear it, or the appearance of the clock will not change, but it sounds will become Thor or the appearance of the clock in the sound of the clock will not change, or the clock will slowly become quieter, and will ultimately they bring you.
As the air is slowly removed from the space around the alarm clock, the sound it produces will gradually become quieter. This is because sound waves require a medium (such as air) to propagate, and in the absence of air molecules, there will be no medium for the sound waves to travel through. Therefore, the clock will become less audible until it can no longer be heard. However, the appearance of the clock would not be affected by the removal of air, so visually it would remain the same.
