Thermodynamics - Result Question 41

43. When $1 kg$ of ice at $0^{\circ} C$ melts to water at $0^{\circ} C$, the resulting change in its entropy, taking latent heat of ice to be $80 cal /{ }^{\circ} C$, is

[2011]

(a) $273 cal / K$

(b) $8 \times 104 cal / K$

(c) $80 cal / K$

(d) $293 cal / K$

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Answer:

Correct Answer: 43. (d)

Solution:

  1. (d) Change in entropy is given by

$\Delta S=\frac{dQ}{T}$ or $\Delta S=\frac{\Delta Q}{T}=\frac{mL_f}{273}$

$\Delta S=\frac{1000 \times 80}{273}=293 cal / K$.