Advanced Science Primary 4 Energy

A flask filled with coloured water has a narrow glass tube. When the flask is placed in hot water, the level of the coloured water in the tube falls slightly before it starts to rise. Why?

A The water is evaporating.
B The flask expands first before the heat reaches the water.
C The water is contracting first.
D The air in the flask is escaping.
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Worked Solution

Step 1: The glass flask gains heat first and expands. Step 2: This expansion increases the internal volume of the flask, causing the water level to drop. Step 3: Once the heat reaches the water, the water expands and rises up the tube.

Correct answer: The flask expands first before the heat reaches the water.

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