AP and TS EAMCET Medical Model Paper 10

(3) A) During melting of ice, volume decreases and hence work is done on system.
du=dQ−dW=80−dW
Here dW is negative. Hence du is more than 80 cal.
B) During boiling of water, volume increases and hence-work is done by system.
du=dQ−dW=540−dW
Here dW is positive. Hence du is less than 540 cal.