Why two holes are made in a sealed tin cane to take out the oil from it?
There is no air inside a completely filled and sealed can. But if two holes are made on the top cover of the can, the air outside the can will enter it through one hole and exert atmospheric pressure on the oil from inside along with the pressure due to oil column, and it will come out of the can from the other hole. That's why there is a need of two holes to take out the oil from a completely sealed tin can.