Pure substances are either elements or compounds. Elements can NOT be separated into other types of matter (physically or chemically). Therefore, elements are pure substances. Ex: Hydrogen gas is a pure substance, as it is made up of only Hydrogen atoms or molecules.
The answer is D.) the process where distribution of molecules is balanced out by their movement.
I believe it would be "bones start to replace cartilage to form the beginnings of a skeleton" since that happens in months 7 and 8
Transpiration. I hope this works.
