Part a
look at the window on the left side of the simulation. it shows the reaction a+
bc ab + c. how does this reaction differ from the reaction by which
ammonia is synthesized?

A + BC → AB + C "single replacement reaction" while ammonia synthesis is a "synthesis reaction".

Explanation:

A single replacement reaction, is a reaction by which one element replaces an/other element in a compound.

It can be represented generically as: A + B-C → A-C + B This will most often occur if A is more reactive than B, thus giving a more stable product.

A synthesis reaction is a type of chemical reaction in which two or more simple substances combine to form a more complex product. The reactants may be elements or compounds, while the product is always a compound.

Example: ammonia synthesis,

N₂ + 3H₂ ⇄ 2NH₃

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.

i just calculated it all out, and not including weekends, and all the different days off. as of this school year (2018-2019) students are spending 2198 hours in school this year