Some chemicals, most often inorganic salts, in the laboratory have the nasty tendency to absorb water from the atmosphere. This property is called hygroscopicity. Anhydrous (water-free) Cupric Perchlorate [Cu (ClO4)2] weighs 262.447g/mol, but after sitting on out on the bench top absorbs water from the air and now weighs 370.540g/mol. How many water molecules did our Cupric Perchlorate absorb?

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.

i think that the answer is c