Concept:Heat lost by the hot water and vessel equals heat gained by the ice to melt and then warm up as water.
Explanation:The vessel's water equivalent is already included in the given effective water mass of 60 g.
First, check whether all the ice melts by cooling to
0∘C.
Heat released by the water and vessel:
Q=60×1×40=2400 cal.
Heat required to melt 15 g of ice:
Qmelt=15×80=1200 cal.
Since
2400>1200, all ice melts and the final temperature is above
0∘C.
Let the final temperature be
T.
Heat lost by the water and vessel:
60(40−T) cal.
Heat gained by the ice:
15×80+15×1×T=1200+15T cal.
Using heat lost = heat gained:
60(40−T)=1200+15T.
Solving,
2400−60T=1200+15T, so
1200=75T.
Thus,
T=16∘C.
Answer:The final temperature of the mixture is
16∘C, which is Option C.