Bằng phương pháp hóa học hãy nhận biết các chất khí không màu trong 4 lọ không nhãn gồm:CO, O2,H2,CO2

What??

Explanation:

I really do want to answer you but i dont understand your letters

waht is that

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.