1) why does a can burst if it is .heated,sealed and cooled suddenly.explain detailly please.

2)perfume sprayed in one corner of the room can be smelt from another corner

a) when a can is heated and sealed then temperature of the air inside the is high and it's pressure is atmospheric. Now when we'll cool then can ; volume of the air inside the can will remain the same and because of lowering of temperature the pressure on the air inside the can will reduce below atmospheric pressure . The pressure difference between the air inside and outside the can  will introduce stresses in this can when these these stresses grow sufficient enough to over come the strength of material of can then the can will burst

b) The perfume evaporates, and its molecules enters the air to be detected as smell. By the process called diffusion, the molecules spread to the air in other parts of the room  from an area of higher concentration to lower.