NDA2026General AbilityGeneral ScienceActual
A 5 , g piece of ice at -20^ C is put into m kg of water at 30^ C temperature. The heat is exchanged only between the ice and the water. The final temperature of the mixture is 0^ C in liquid phase. What is the value of m in kg?
Options
- A0.050
- B0.010
- C0.015
- D0.150
Correct answer
C. 0.015
Step-by-step solution
Heat gained by ice to reach 0^ C in the liquid phase consists of the heat required to raise its temperature to 0^ C and the latent heat of fusion to melt it. Using the specific heat of ice s_ ice = 0.5 cal/g ^ C and latent heat of fusion L = 80 cal/g , the total heat gained is: Q_ gained = m_ ice s_ ice T + m_ ice L Q_ gained = 5 0.5 20 + 5 80 Q_ gained = 50 + 400 = 450 cal Heat lost by water to cool from 30^ C to 0^ C is: Q_ lost = m_ water s_ water T Since the mass of water is m kg = 1000m g and s_ water = 1 cal/