Glass and iron are both conductors of heat. However, glass is a poor conductor of heat and iron is a good conductor of heat.

1. (a)Describe, using ideas about particles, how the conduction of heat takes place in glass and in iron. You should make it clear why iron is a better conductor of heat. conduction in glass ............................................................................................................................................................................. ............................................................................................................................................................................. ............................................................................................................................................................................. ............................................................................................................................................................................. conduction in iron ............................................................................................................................................................................. ............................................................................................................................................................................. ............................................................................................................................................................................. ............................................................................................................................................................................. [4][4]
2. (b)(i)Fig. 4.1 shows apparatus used to show expansion. [Figure 4.1 (glass tube, liquid level X, glass flask, water, heat source)] The glass flask, full of water, is heated. A student is surprised when the liquid level X in the glass tube falls for a few seconds before it rises. Suggest why the liquid level falls and why it then rises. ............................................................................................................................................................................. ............................................................................................................................................................................. ............................................................................................................................................................................. ............................................................................................................................................................................. [2][2]
3. (b)(ii)Describe how heat is transferred throughout the water in the glass flask. ............................................................................................................................................................................. ............................................................................................................................................................................. ............................................................................................................................................................................. ............................................................................................................................................................................. [2][2]

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