Consider the following statements about a thermos flask
1.It is a practical device in which the heat flowing into or out of the system by conduction, convection or radiation is reduced as much as possible.
2.It consists of a double-walled glass vessel.
3.The heat transfer by convection is minimised by silvering the surfaces and the radiation is minimised by evacuating the space between the walls.Of these, the correct ones are
Option:(d)