Question

when hot and cold water mixed,the entropy?increase or decrease?

Answer 1

When hot and cold water mixed together the entropy increases.

Hope it helps...

Answer 2

when a hot and cold fluid are mixed they cannot unmix without providing external heat or work. This means the entropy has changed, more exactly it has decreased when compared to the entropy of hot water and electricity increased compared to the entropy of cold water. What you have to care about is amount of work or heat you are losing.