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IGCSE · 2 · multiple choice

Thermal physics · Question 4

Thermal physics · Original GioPhysics question with a detailed, mark-by-mark answer guide.

Demand
demanding
Marks
1
Topics
1
Answer
Complete
multiple choice1 mark

Which statement about evaporation is correct?

  1. A

    It happens throughout the liquid, at one fixed temperature.

  2. B

    It happens only at the surface, at any temperature below the boiling point.

  3. C

    It raises the temperature of the liquid that is left behind.

  4. D

    It happens faster when the air above the liquid is still and humid.

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Answer overviewCorrect answer: B — It happens only at the surface, at any temperature below the boiling point.
01

Answer and reasoning

1 mark
How to approach it

Predict from the governing principle before looking for a matching option. Then reject alternatives by checking direction, units, limiting behaviour or the physical meaning of each statement.

  1. 1

    The correct choice is B: It happens only at the surface, at any temperature below the boiling point.

  2. 2

    A describes boiling, which is the distinction the item is set on. C reverses the cooling effect — the fastest molecules leave, so the mean energy of those remaining falls. D reverses the effect of a draught.

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