Question

Give reason a Ballon collapses when air is removed from it.

Answer 1

When air is filled inside  a balloon, the air molecules exert pressure on the walls of balloon. The air molecules are moving randomly and are also filled with pressure into the balloon. These air molecules then exert a constant and uniform presssure on the walls of the balloon and keep it inflated.

Now when the air is removed, the pressure that the air molecules were exerting on the walls is gone. So the balloon collapses.