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JAMB Physics 2006 Question 45

Question 45

Change of State and Vapours

A drop of petrol makes a finger colder than a drop of water would because

  1. A.petrol takes its latent heat of fusion from the finger.
  2. B.petrol takes its latent heat of vaporization from the finger.
  3. C.water has higher surface tension than petrol.
  4. D.water is more viscous than petrol.
Show the answer and explanation

Answer: B (petrol takes its latent heat of vaporization from the finger.)

Explanation

Petrol evaporates much faster than water, and the latent heat it needs to evaporate is taken from the finger, which cools it.