Chemistry common assessment 3rd 9 weeks

explanation:

i think option no d is the correct answer

c is the answer because when something is left after something evaporates that shows the chemical change.

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.