Question

A device in which the loss of heat due to conduction ,Convection and radiation is minimised is

Answer 1

ThermosFlask can be one such device, in which there are specific mechanisms to minismise the loss of heat due to conduction, convection and radiation

Answer 2

The device is vacuum flask. The  device is made in such a way that it minimizes heat lose ,thus keeping substances in it hot or warm for long time. The device has its surface covered with silver to minimise heat lose through  radiation and is made of plastic to prevent heat lose by conduction.