7. What is the maximum amount of NaCl that can be
dissolved (in 100g of water) at 90°C?

Maximum amount of NaCl that can be Dissolved in 100g of water at 90'C

Explanation:

In fact, you can expect to be able to dissolve no more than 40 g of sodium chloride per 100 g of water at 80∘C . So, at 80∘C , you will have an unsaturated solution if you dissolve less than 40 g of sodium chloride, and a saturated solution if you dissolve about 40 g of sodium chloride

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.