Aradioactive isotope has a half-life of 2.5 years. which fraction of the original mass remains unchanged after 10 years?

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.

increased stability in the completion of fluorine's outer shell.