Evaluate each scenario described to determine the direction of heat flow

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

Which class of molecules functions as chemical signals? hormones water carbohydrates proteins

When balancing a chemical equation: