Aradioactive isotope of vanadium, v, decays by producing a  particle and gamma ray. the nuclide formed has the atomic number: a) 22 b) 21 c) 23 d) 24 e) none of these

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.