Q.

Water of mass m gram is slowly heated to increase the temperature from T1 to T2. The change in entropy of the water, given specific heat of water is 1 Jkg–1 K–1, is          [2025]

1 zero  
2 m(T2–T1)  
3 m ln (T1T2)  
4 m ln (T2T1)  

Ans.

(4)

dQ = msdT

dS=dQT=msdTT

△S=∫msdTT=ms ln TfTi

△S=m ln T2T1 as s=1