Phase of a writing strategy involves deciding on the topic and the purpose of the essay.
a. prewriting
b. drafting
c. revising
d. editing

Phase of a writing strategy which involves deciding on the topic and the purpose of the essay is A. prewriting. During prewriting, which is similar to brainstorming, you just want to decide what you want to write about. Here, you may write as many ideas as you can, take some notes, and later on choose which ones you will incorporate in your text, and which ones you will discard.

1) noble gases2) by increasing atomic number3) noble gases