Un catión tetravalente tiene 50 electrones, si la cantidad de neutrones excede en 20 a su número atómico; hallar su número de masa. a) 162 b) 128 c) 281 d) 234

I don't speak espanol

Explanation:

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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.