Heat loss in a thermos flask can be prevented by

The correct answer is [D] Conduction, convection, and radiation. A thermos flask is designed to minimize heat loss through all three mechanisms. The vacuum between the inner and outer walls of the flask effectively prevents heat transfer by conduction and convection. Since there is no medium for these processes to occur in the vacuum, they are significantly reduced. To tackle heat loss through radiation, the inner surfaces of the flask are usually coated with a reflective material like aluminum. This reflective coating helps to reflect infrared radiation back into the liquid, maintaining its temperature. The combination of these features ensures that the thermos flask is highly efficient at keeping its contents hot or cold for extended periods. By addressing all three methods of heat transfer, the thermos flask exemplifies a practical application of thermal insulation principles, making it an essential tool for preserving the temperature of liquids.