Please help me out with this question

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? a. a compound b. an element c. a heterogeneous mixture d. a homogeneous mixture

Elements in group 2 are all called alkaline earth metals. what is most similar about the alkaline earth metals?

How do dying stars contribute to the formation of planets