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## Homework Statement

Calculate the change in entropy of the universe as a result of the following process:

A copper block of mass 0.4 kg and heat capacity 150 JK

^{-1}at 100

^{0}C is placed in a lake at 10

^{0}C.

**2. The attempt at a solution**

change in entropy (copper) = mc ln (T

_{2}/ T

_{1})

change in entropy (lake) = mc ( T

_{1}- T

_{2}) / T

_{2}

where T

_{1}= 373 K, T

_{2}= 283 K.

The answer given is 6.3 JK

^{-1}. which is differ from the answer I got. May I know if i have done any careless mistake?