2kg of ice at `-20^@C` is mixed with 5kg of water at `20^@C` in an insulating vessel having a negligible heat capacity. Calculate the final mass of water remaining in the container. It is given that the specific heats of water & ice are `1kcal//kg//^@C` and `0.5`
`kcal//kg//^@C` while the latent heat of fusion of ice is `80kcal//kg`

Answer

B

Explanation

`2kg "ice" (-20^(@)C)" "5Kg"water" (20^(@)C)`
`downarrow20 Kcal " "downarrow100Kcal`
2Kg "ice"(0^(@)C)"
"5Kg"water"(0^(@)C)`
`downarrow160Kcal`
`2Kg"water"(0^(@)C)`
`RightarrowFinal temperature
Amount of ice melted
`=(100-20)/(80)=1Kg`
`implies` Final mass of water
`=5+1=6Kg`