Multiple choice

Ice at $20 C $is added $to \ 50 g$ of water at $40C$.When the temperature of the mixture reaches $0C$,it is found that $20 g$ of ice is still unmelted. The amount of ice added to the water was close to (specific heat of water $=4.2J/g/^oC)$ Specific heat of Ice $=2.1\,J/g/^oC$ Heat of fusion of water at $0^oC=334j/g$

  1. $50g$
  2. $40g$
  3. $60g$
  4. $100g$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Interpreting the ice temperature as -20 C, the water releases 50×4.2×40 = 8400 J on cooling to 0 C. For m grams of ice, 20 g melts, so m×2.1×20 + 20×334 = 8400, giving m = 40 g.

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