What pair of ions have the same number of electrons? 1) Ca2+ and Cl-
2) Ca2+ and Mg2+
3) Na+ and Cl-
4) Mg2+ and Cl-
5) Li+ and O2-

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.

im pretty sure its b

while cooking a piece of 1/2 pound beef steak, a cast iron pan (2.4kg in weight) was heated 260 celsius.