Who was the first to propose the idea of atoms?

Ageologist determines that a sample of a mineral can't be scratched by a steel nail but can be scratched by a masonry drill bit. based on this information, the sample mineral has to be softer than a. orthoclase. b. fluorite. c. apatite. d. corundum.

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation:

What is the empirical formula of c6h18o3? ch3o c2h5o c2h6o c2h5o5