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GATE 2020 CH – Question 30

Heat Transfer · Boiling, condensation and evaporation · 1 mark · Multiple choice

The Leidenfrost phenomenon refers to

  1. Vapour condensation on a cold surface.
  2. Heat exchange between two solids.
  3. Frost melting.
  4. Film boiling and evaporation of droplets on a very hot surface.

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Show answer and explanation

Correct answer: (D) Film boiling and evaporation of droplets on a very hot surface.

Explanation

On a surface far above the liquid’s boiling temperature, a droplet can generate a persistent vapour layer underneath itself. This insulating cushion reduces direct contact and supports film-boiling behaviour, the Leidenfrost phenomenon. Thus D; ordinary condensation or frost melting describes different processes.

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