Name the substance whose weight produces atmospheric pressure.

If a vacuum is created between two Magdeburg hemispheres joined together, they cannot be separated easily, What presses the hemispheres together ?

What makes a balloon get inflated when air is filled in it?

Where is the pressure greater, 10m below the surface of the sea or 20m below the surface of sea?

What force acting on, an area of 0.5 m ² will produce a pressure of 500 Pa?