The mass of a deuterium nucleus 2 1 H is less than its component's masses. Calculate the binding energy in mev 3.521
1.93
2.224

- decrease the number of plants and animals living in the water.

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.