UPSC Prelims 2003·GS1·science-and-technology·science and technology

Consider the following statements: 1. Steam at 100° C and boiling water at 100° C contain same amount of heat. 2. Latent heat of fusion of ice is equal to the latent heat of vaporization of water. 3. In an air-conditioned, heat is extracted from the room air at the evaporator coils and is rejected out at the condenser coils. Which of these statements is/are correct?

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Last updated 23 May 2026, 3:31 pm IST
  1. A1 and 2
  2. B2 and 3
  3. COnly 2
  4. DOnly 3Correct

Explanation

Statement 1 is incorrect because steam at 100 degrees Celsius contains more heat than boiling water at the same temperature. This extra energy is known as the latent heat of vaporization, which is required to convert water into steam without changing its temperature. Statement 2 is incorrect because the latent heat of fusion of ice is significantly lower than the latent heat of vaporization of water. It takes much more energy to convert boiling water into steam than it does to melt ice into water. Statement 3 is correct because it accurately describes the refrigeration cycle in an air conditioner. The evaporator coils inside the room absorb heat from the air, causing the refrigerant to evaporate. This heat is then carried to the external condenser coils, where the refrigerant releases the heat to the outside environment and turns back into a liquid. Therefore, only statement 3 is correct, making option D the right answer.
science-and-technology: Consider the following statements: 1. Steam at 100° C and boiling water at 100° C contain same amount of heat. 2. Latent

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