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JAMB Physics 1982 Question 37

Question 37

Change of State and Vapours

A heater marked 50 W will evaporate 0.005 kg of boiling water in 50 seconds. The specific latent heat of vaporization of water in J/kg is

  1. A.5.0 × 106
  2. B.1.0 × 106
  3. C.2.5 × 106
  4. D.2.5 × 105
  5. E.5.0 × 105
Show the answer and explanation

Answer: E (5.0 × 105)

Explanation

Heat supplied = Pt = 50 × 50 = 2500 J. L = 2500 ÷ 0.005 = 5.0 × 105 J/kg.