The present book, Physics and Chemistry is one among the five books of the series, Children's Encyclopedia – The World of Knowledge. The book has been broadly divided into two parts- Physics and Chemistry. The part that deals with Physics contains simple and fully coloured illustrative chapters on Energy, Magnetism, Electricity, Light, Sound, Force, Motion, Atomic and Nuclear Energy, Pressure, Relativity, etc. The second part exclusively deals with Chemistry containing a detailed and diagrammatic description of Matter and its Properties, Mass, Volume and Density, all about Atoms, Molecules and Elements, Compounds and Mixtures, Reactions and Changes between Solids, Liquids and Gases, etc. Hence dear readers, grab the book as soon as you can, for it's a treasure trove of knowledge and information, and if you happen to be a school student, you can even use it as a reference book or guide. Happy Reading and Learning too!