Cracks in rocks chemical or mechanical

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

What is the temperature of one mole of helium gas at stp?

Is a pencil falling to the floor anon contact force, a force, or a contact force