quantity of heat flowing in one second through one cm cube of material when opposite faces ^re maintained at a temperature difference of 1°C

quantity of heat flowing in one second through a slab of the material of area one cm square, thickness 1 cm when its faces differ in temperature by 1°C

heat conducted in unit time across unit area through unit thickness when a temperature difference of unity is maintained between opposite faces

all of the above

aluminium

steel

brass

copper

high thickness of insulation

high vapour pressure

less thermal conductivity insulator

a vapour seal

electric heater

steam condenser

melting of ice

boiler.

it is impossible to transfer heat from low temperature source to t high temperature source

heat transfer by radiation requires no medium

all bodies above absolute zero emit radiation

heat transfer in most of the cases takes place by combination of conduction, convection and radiation