The atomic symbols of nitrogen and oxygen are N and O, respectively. The chemical formula of a particular substance is NO2.
Which of the following is a correct description of the substance?
A. an element made up of 2 nitrogen atoms and 2 oxygen atoms
B. a compound made up of 1 nitrogen atom and 2 oxygen atoms
C. an element made up of 1 nitrogen atom and 1 oxygen atom
D. a compound made up of 2 nitrogen atoms and 2 oxygen atoms