Describe a simple experiment to illustrate that air exerts pressure.
EXPERIMENT : Take a tin-can having air tight cap (screw cap). Remove cap and boil some water in it, so that steam comes out and in this way air from inside goes out. While boiling replace the cap and allow it to cool. Vapours inside condense and form water creating vacuum above them. We see the can crumbles due to air pressure from outside. This proves that air exerts pressure.