A Dewar flask is a container designed to prevent heat transfer so that its contents remain hot or cold for a longer period of time. It consists of a double-walled container
in which most of the air has been removed from the space between the walls. Some
household thermoses are Dewar flasks. What heat-transfer processes are prevented
by removing the air between the walls?
a. Conduction and radiation
b. Conduction and convection
C. Convection and radiation
D. Conduction , convection , and radiation