Quote by Outrageous
Is that possible to calculate entropy when dq=+100J , temperature change from 271K to 273K ?
Ice melt until 273K , not an isolated system.
Or I can only calculate entropy only at constant temperature?

Start with:
[itex]\Delta S = \int_{rev} dq/T[/itex]
So in order to determine the change in entropy of the ice, you have to break the process into two parts:
first the ice is warmed up from 271K to 273K. What is dq in terms of dT and the mass of the ice? (hint: you have to know the specific heat capacity of ice).
second: the ice melts all at 273K, so the ΔS will be easy to calculate.
Then all you have to do is add up the changes in entropy to get the total change in entropy.
AM