Can u pls help i have 5 minutes left pls

pure substance: iron,copper

impure substance: water,charcoal

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.

o conteúdo de calor de um sistema é igual à entalpia apenas para um sistema que é constante