Medium MCQ +4 / -1 PYQ · JEE Mains 2020

A calorimeter of water equivalent 20 g contains 180 g of water at 25oC. ‘m’ grams of steam at 100oC is mixed in it till the temperature of the mixure is 31oC. The value of ‘m’ is close to :
(Latent heat of water = 540 cal g–1, specific heat of water = 1 cal g–1 oC–1)

  1. A 2.6
  2. B 2 Correct answer
  3. C 4
  4. D 3.2

Solution

Given Temp of mixture = 31°C <br><br>180×1×(31-25) + 20×(31-25) = m×540 + m×1×(100-31) <br><br>$\Rightarrow$ 180×6 + 20×6 = 540m + 100 m - 31m <br><br>$\Rightarrow$ 1080 + 120 = 640 m - 31m <br><br> $\Rightarrow$ 1200 = 609m <br><br>$\Rightarrow$ m = ${{1200} \over {609}}$ = 1.97

About this question

Subject: Physics · Chapter: Thermodynamics · Topic: Heat Transfer

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