Chapter 2:

12. Kinetic energy is energy in action. It is seen in constant movement of tiny particles of matter as well as in larger objects. Potential energy is stored energy which is inactive energy that has the potential or the capability to do work but is not presently doing so.
13. Chemical element is a unique substance that cannot be broken down into simpler substances by ordinary chemical methods. Carbon, Oxygen, Hydrogen, and Nitrogen are the four elements that form the bulk of body matter.
14. Solutions are homogeneous mixtures of components that may be gases, liquids or solids. Colloids which are also called emulsions here heterogeneous mixtures that often appear translucent or milky. Although solute particles are larger than those in true solutions, they still do not settle out. Suspensions are are also heterogeneous mixtures with large, often visible solutes that tend to settle out.
15. When shared electrons are shared equally between the atoms of a molecule the molecules formed are electrically balanced and are called non polar molecules because they do not have separate + and ­ poles of charge. On the other hand unequal sharing of electron pair sharing results in molecules called polar molecules.