A panic attack is an exaggeration of your bodyâs normal response to fear, stress or excitement. It is the rapid build-up of overwhelming physical sensations, such as: 1  a pounding heartbeat. 2  feeling faint. 3  sweating. 4  nausea (feeling sick).
Since four elements must be present for the combustion process to occur (fuel, heat, an oxidizing agent, and a chemical chain reaction), a fire can be extinguished by removing any one of these four elements.
In decomposition reactions, one reactant forms two or more products. The reactant is decomposed by energy sources such as heat, light, or electricity. Combustion reactions occur when compounds rapidly combine with oxygen and require some kind of ignition like a flame. Other Tips: Seven frequently used elements occur naturally as diatomic molecules: H 2, O 2, N 2, Cl 2, Br 2, I 2. Ionic species are usually in aqueous solution, (aq); States of matter,(s),(l),(g) should be included after the chemical symbol.