[tex] \mathfrak{\huge{ \mathfrak{ \underline{ Answer }}}\: ✓ }[/tex]
We know, hot water has more energy than the cold water , so when cold water is added in the beaker then heat transfer occurs from hot water to cold water to balance the Energy, causing the drop of temperature from 70° C to 40° C.
Note : Heat transfers occurs from hotter object to cooler one.
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