Standard Science Primary 4 Energy

Why is air a good material to use for a thermal flask (between the double walls)?

A It is a poor conductor of heat.
B It is a good conductor of heat.
C It is transparent.
D It expands easily.
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Worked Solution

Step 1: Thermal flasks aim to keep liquids hot/cold by reducing heat transfer. Step 2: Poor conductors (insulators) slow down heat flow. Step 3: Air is an excellent insulator.

Correct answer: It is a poor conductor of heat.

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