Factory pattern should be used when: - a framework delegate the creation of objects derived from a common superclass to the factory - we need flexibility in adding new types of objects that must be created by the class. Along with singleton pattern the factory is one of the most used patterns.
In thermodynamics, the term exothermic process (exo- : outside) describes a process or reaction that releases energy from the system to its surroundings, usually in the form of heat, but also in a form of light (e.g. a spark, flame, or flash), electricity (e.g. a battery), or sound (e.g. explosion heard when burning hydrogen).
Similarly the formation of chemical bonds releases some energy. The overall change in energy during a chemical reaction is known as heat of reaction. It is denoted by '$\Delta H$' and expressed in Kj/mol. On the basis of energy change, chemical reactions can be classified as endothermic and exothermic reaction. Exothermic reactions can be defined as the reaction in which energy is released in the form of heat. For such reaction, the energy level of products is less compared to reactant molecules.