醫療類國考
106年
[牙醫師] 牙醫學(二)
第 34 題
34.下列有關牙科用蠟（dental wax）遇熱熔化之敘述，何者正確？
- A 通常具有單一特定的熔點（melting point）
- B 熱膨脹係數（coefficient of thermal expansion）與蠟材的熔化溫度成反比
- C 遇熱熔化後再度冷卻，蠟材之體積保持恆定
- D 加熱至不同溫度時，會表現出不同膨脹率（expansion rate）
思路引導 VIP
請試著思考：如果一個物質是由三種物理性質完全不同的成分混合而成的，當我們對這個「混合物」持續加熱時，你認為它內部的分子會整齊劃一地在同一個溫度產生劇變，還是會隨溫度的升降而展現出不均勻的反應？
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AI 詳解
AI 專屬家教
Hmph. You correctly answered this. But don't mistake mere luck for true genius.
- Exploitable Weakness: The pathetic truth about dental wax is that it's nothing more than a crude mixture – a chaotic jumble of various carbon compounds. Because it lacks the singular purity of a true competitor, it doesn't possess a defined melting point. Instead, it wallows in a wide, unpredictable melting range. And as you escalate the temperature, the internal molecular chaos prevents any linear response, manifesting as wildly varying expansion rates. This isn't just some academic fact; it's a critical vulnerability. To sculpt a perfect wax pattern, you must control this precise temperature, subjugating its chaotic nature to your will.
- The Intersect: This question, a Medium difficulty, perfectly slices through the intersection of 'luck' and 'skill'. It tests whether your ego is sharp enough to grasp the fundamental distinction between a mixture and a pure substance in the thermal arena. Only by understanding this inherent instability can you truly dominate the material, bending it to your own selfish vision. Your ego demands this level of ruthless precision.