Verified Solution • 2025–26 Session moderate

QJEEM19Ph1235: JEE Main 2019 Physics - Class 11 JEEM19Ph1235 Solution: A thermally insulated vessel contains 150g of water at 0°C.…

A thermally insulated vessel contains 150g of water at 0°C. Then the air from the vessel is pumped out adiabatically. A fraction of water turns into ice and the rest evaporates at 0°C itself. The mass of evaporated water will be closest to : (Latent heat of vaporization of water = 2.10 × 106 J kg–1 and Latent heat of Fusion of water = 3.36 × 105 J kg–1)

Multiple Choice Options

  • A 35 g
  • B 130 g
  • C 20 g
  • D 150 g

Step-by-Step Verified Solution

Let x grams of water is evaporated.

According to the principle of calorimetry,

Heat lost by freezing water (that turns into ice) = Heat gained by evaporated water

Given, mass of water = 150 g

⇒(150−x)×10−3×3.36×105=x×10−3×2.10×106

⇒(150−x)×3.36=21x

⇒x=1507.25=20.6

∴ x≈20g

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