Zoe is investigating the composition of substance a, an unknown substance. using chemical processes, she analyzes substance a and determines it is composed of sodium, oxygen, and hydrogen atoms in a ratio of 1 : 1 : 1. what is substance a?

The substance is  NaOH

Explanation:

To find the number of atoms of each element we multiply coefficient and the subscript  

For example contains  

5 × 1 = 5,Ca atoms and

5 × 2 = 10, Cl atoms  

Sodium hydroxide is NaOH which contains

1, Na atom and

1, O atom and

1, H atom  

Hence the ratio is 1 : 1 : 1