Radioactive tracer such as a cell or tissue, or as a flow tracer to track fluid flow. Radioactive tracers are also used to determine the location of fractures created by hydraulic fracturing in natural gas production. Radioactive tracers form the basis of a variety of imaging systems, such as, PET scans, SPECT scans and technetium scans. Radiocarbon dating uses the naturally occurring carbon-14 isotope as an isotopic label. Isotopes of a chemical element differ only in the mass number. For example, the isotopes of hydrogen can be written as H, H and H, with the mass number at top left. When the
Hydrochloric acid , Bulgarian: солна киселина, Russian: соляная кислота, , Korean: 염산, and Taiwanese: iâm-sng. Gaseous HCl was called "marine acid air". The old (pre-systematic) name "muriatic acid" has the same origin ("muriatic" means "pertaining to brine or salt", hence "muriate" means hydrochloride), and this name is still sometimes used. The name "hydrochloric acid" was coined by the French chemist Joseph Louis Gay-Lussac in 1814. Hydrochloric acid has been an important and frequently used chemical from early history and was discovered by the alchemist Jabir ibn Hayyan around the year 800 AD. Aqua regia, a mixture consisting of hydrochloric and nitric acids,