An authors purpose for writing is to inform how do writers accomplish this purpose

When an author wants to inform, usually they will give suggesting words, such as procedure, reports, explain(ing/tion), etc.

Explanation:

You can also find this out when a tone in text is serious. If the author is trying to tell you something important, like why you shouldn't drink too much soda, they aren't going to be joking around, saying stuff like, "Unless you want your teeth to make you look 80 when you're 20, don't drink soda."

Hope this helps! ;)

the author develops a cold, and scared tone. making the reader shudder with fear, and suddenly become cold. i'm guessing that he's writing a scary novel, or maybe about a chilly december night.