Question

During the melting of a slab of ice at 273K at atmospheric pressure,
A. positive work is done by the ice-water system on the atmosphere
B. positive work is done on the ice-water system by the atmosphere
C. the internal energy of the ice-water system increases
D. the internal energy of the ice-water system decreases

Answer 1

Correct Answer - B::C
There is a decreases in volume during melting of an ice slab at `273K` . Therefore, negative work is done on the by ice water system on the atmosphere or positive work is done on the ice-water system by the atomsphere. Hence option `(b)` is correct. Second, heat is absorbed during melting (i.e., `dQ` is positive) and as we have seen, work done by icewater system is negative `(dW "is negatvie".)` Therefore, from the first law of thermodynamics, `dU=dQ-dW`, with change in internal energy of ice-water system, `dU` will be positive or internal energy will increase.