20 points! the cdc (centers for disease control) is a federal agency that monitors the spreading of various diseases and health issues. they have done extensive research on the effects of tobacco on a person's health. the cdc does a study on smoking with the hypothesis, "if a person smokes more cigarrettes, then they are more likely to develop heart disease". which of the following should be a controlled variable for this experiment? choose all that apply. 1. amount of smoking a person does 2. weight class of the person 3. state where the person lives 4. whether or not the person develops heart disease

if two electrons have the same n, the same ℓ, and the same ml, then they are in the same orbital. the pauli exclusion principle states that no two identical fermions (a fancy word for electrons and other subatomic particles like electrons) may occupy the same quantum state in an atom simultaneously.

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.