EXTRA CREDIT How much heat must be added to a 75.0-gram sample of water to raise the temperature from -20°C (sold) to 20°C (liquid), knowing that water melts at
0°C? All pertinent constants can be found below:
90 - 2.00 J/g°C
water 4.18 1/3°C
- 6,01 kJ/mol
ΔΗω

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.

it's c (engineer's do their work with mechanical stuff not on any living being)

it is thermal conduction according to apex : )