The part of the Earth that is tilted towards the Sun changes throughout the year as shown in the diagram. In which position is the Northern Hemisphere experiencing fall? Select one: O position B
O position C
O position A
O position D

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