Properties Of Solids And Liquids Question 70

Question: 1 g of a steam at 100°C melt how much ice at 0°C? (Latent heat of ice = 80 cal/gm and latent heat of steam = 540 cal/gm) [Pb. PET 2000]

Options:

A) 1 gm

B) 2 gm

C) 4 gm

D) 8 gm

Show Answer

Answer:

Correct Answer: D

Solution:

Suppose m gm ice melted, then heat required for its melting $ =mL=m\times 80cal $

Heat available with steam for being condensed and then brought to 0°C $ =1\times 540+1\times 1\times (100-0)=640cal $

therefore Heat lost = Heat taken therefore $ 640=m\times 80 $

therefore $ m=8gm $

Short trick: You can remember that amount of steam (m’) at 100°C required to melt m gm ice at 0°C is $ m’=\frac{m}{8} $ . Here, $ m=8\times m’=8\times 1=8gm $



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