PLEASE HELP ASAP ;( make sure you fill out the table carefully, it is important to recognize that the first four columns are b) for the elements and/or particles at the beginning of the reaction. the four columns on the right are for the final products. be sure your initial total mass is equal to the final total mass, as per the law of conservation of energy.
BASICALLY IF YOU HAVE THIS DONE I NEED HELP W THE ENTIRE PROJECT..

the answer would be a

i just learnt this recently but i need to look through my notes again

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.