Each of the two days of the year when neither hemisphere is tilted toward or away from the Sun is called a(n)

first one is the correct answer

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.

some sources quote the lethal dose, for an average 170lbs opiate-naive individual is between 75 and 375 mg