Class 9 Chemistry Test Test Time Explore various categories of non-fiction books. Matter in Our Surroundings Explore the physical nature of matter, its states, and how it changes form through processes like evaporation and boiling. Is Matter Around Us Pure? Learn about mixtures and compounds, the types of solutions, suspensions and colloids, and their separation techniques. Atoms and Molecules Understand the laws of chemical combination, molecules of elements and compounds, and how to write chemical formulae. Structure of the Atom Study the atomic models by Dalton, Thomson, Rutherford, and Bohr, and concepts like atomic number, mass number, valency, isotopes, and isobars.