Thermos flask keeps hot liquid hot and cold liquid cold by:
A
Cooling
B
Using coolant
✓
Preventing heat loss
D
Heating
✓
Answer
Correct option: C.
Preventing heat loss
The silver coated surface becomes shiny, so it reflects all the heat inside the wall, and it does not allow the heat to go out. And the layer of glass wall thermo flask is thin, so it prevents the loss of heat by conduction.
Therefore, the thermo flask keeps cold liquid cold and hot liquid hot.
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