Q 12
Question

You are provided with an experimental setup as shown in Fig. 9.26a and 9.26b. On keeping the test tube (Fig. 9.26b) in a beaker containing hot water (~70°C), the water level in the glass tube rises. How does it affect the density?

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Answer
The density decreases.

Explanation

  • The hot water heats the water in the test tube.
  • The water expands, so its volume increases.
  • The mass stays the same.
  • Since density = mass ÷ volume, the density decreases.
Density
=
\( \dfrac{\text{Mass (same)}}{\text{Volume (increased)}} \;\Rightarrow\; \text{Density decreases} \)
Heating expands the water, raising its volume at constant mass, so its density decreases.
← Back to concept: 9.5.2 Effect of temperature on density
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