Answer
See explanation
Work Step by Step
(a) The heat transfer between the ice of 0°C and the surrounding of 20°C. It is a natural process since heat travels from hot place to cold place that made the ice spontaneously melt and does not require engines. This means the process is irreversible.
(b) $ΔS_{net} = ΔS_{ice} + ΔS_{room} $
$ΔS_{net} = \frac{mL_f}{T_{ice}} + \frac{mL_f}{T_{room}}$
$ΔS_{net} = \frac{(15.0 kg)(334 × 10^3 J/kg)}{273.15 K} + \frac{(-15.0 kg)(334 × 10^3 J/kg)}{293.15 K}$
$ΔS_{net} = +1251 J/K$
Yes it is consistent with the answer in (a). Entropy of irreversible process is always positive since the degree of disorder is always increasing.
