Â· 43 comments. in Facts. An intelligence quotient, or IQ, is a score derived from one of several standardized tests designed to assess intelligence. The abbreviation âIQâ comes from the German term Intelligenz-Quotient, originally coined by psychologist William Stern.
Lower explosive limit. Lower explosive limit (LEL): The lowest concentration (percentage) of a gas or a vapor in air capable of producing a flash of fire in presence of an ignition source (arc, flame, heat). The term is considered by many safety professionals to be the same as the lower flammable limit (LFL).
The six noble gases are found in group 18 of the periodic table. They are Helium, Neon, Argon, Krypton, Xenon, and Radon in order of increasing atomic weight. These elements were considered to be inert gases, as they have a closed-shell configuration, until the 1960's, because their oxidation number of 0 prevents the noble gases from forming compounds readily. This was found to be incorrect in 1962 when Neil Bartlett succeeded in making the first complex xenon compound.