From the information given,
mass of water, m = 20 kg
Temperature of water, θ = 0 C
we would convert the temperature to kelvin by adding 273. Thus,
θ = 0 + 273 = 273 K
Latent heat of fusion of water, hf = 3.33 x 10^5 j/kg
In this scenario, phase change occurs at constant temperature. Thus,
total heat interaction during phase change is
dQ = mhf = 20 x 3.33 x 10^5 = 6.66 x 10^6 J
Change in entropy, dS = dQ/θ = 6.66 x 10^6/273
dS = 24.396 x 10^3 j/k
Converting to Kj/k, we would divide by 1000. Thus,
dS = 24.396 KJ/k
There would be a decrease in entropy since the phase transition is towards lower internal energy.Thus,
dS = - 24.4 KJ/k