Please answer the following question: Information: - Radon is a chemical element with symbolRn and atomic number86. It is a radioactive, colorless, odorless, tasteless noble gas. It occurs naturally as an intermediate step in the normal radioactive decay chains through which thorium and uranium slowly decay into lead; radon, itself, is a decay product of radium. Its most stable isotope, Rn, has a half-life of 3.8 days. Since thorium and uranium are two of the most common radioactive elements on Earth, and since their isotopes have very long half-lives, on the order of billions of years, radon will be present long into the future. - Thorium is a chemical element with symbol Th and atomic number 90. A radioactive actinide metal, thorium is one of only two significantly radioactive elements that still occur naturally in large quantities as a primordial element (the other being uranium). It was discovered in 1829 by the Norwegian amateur mineralogist Morten Thrane Esmark and identified by the Swedish chemist Jons Jacob Berzelius, who named it after Thor, the Norse god of thunder. - In nuclear physics, a decay product (also known as a daughter product, daughter isotope or daughter nuclide) is the remaining nuclide left over from radioactive decay. Radioactive decay often proceeds via a sequence of steps (decay chain). For example, U decays to Th which decays to Pa which decays, and so on, to Pb (which is stable): - Half-life (abbreviated t) is the time required for a quantity to reduce to half its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo, or how long stable atoms survive, radioactive decay. The term is also used more generally to characterize any type of exponential or non-exponential decay. For example, the medical sciences refer to the biological half-life of drugs and other chemicals in the body. The converse of half-life is doubling time. - In chemistry, esters are chemical compounds derived from an acid (organic or inorganic) in which at least one OH (hydroxyl) group is replaced by an Oalkyl (alkoxy) group. Usually, esters are derived from a carboxylic acid and an alcohol. Glycerides, which are fatty acid esters of glycerol, are important esters in biology, being one of the main classes of lipids, and making up the bulk of animal fats and vegetable oils. Esters with low molecular weight are commonly used as fragrances and found in essential oils and pheromones. Phosphoesters form the backbone of DNA molecules. Nitrate esters, such as nitroglycerin, are known for their explosive properties, while polyesters are important plastics, with monomers linked by ester moieties. - Carbonic acid is a chemical compound with the chemical formula HCO (equivalently OC(OH)). It is also a name sometimes given to solutions of carbon dioxide in water (carbonated water), because such solutions contain small amounts of HCO. In physiology, carbonic acid is described as "volatile acid" or "respiratory acid", because it is the only acid excreted as a gas by the lungs. It plays an important role in the bicarbonate buffer system to maintain acidbase homeostasis. - Carbon (from "coal") is a chemical element with symbol C and atomic number 6. It is nonmetallic and tetravalentmaking four electrons available to form covalent chemical bonds. Three isotopes occur naturally, C and C being stable, while C is a radioactive isotope, decaying with a half-life of about 5,730years. Carbon is one of the few elements known since antiquity. - In chemistry and physics, the atomic number of a chemical element (also known as its proton number) is the number of protons found in the nucleus of an atom of that element, and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z. The atomic number uniquely identifies a chemical element. In an uncharged atom, the atomic number is also equal to the number of electrons. - Imereti (Georgian: ) is a region in Georgia situated along the middle and upper reaches of the Rioni river. It consists of the following Georgian administrative-territorial units: - Radium is a chemical element with symbolRa and atomic number88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, but it readily combines with nitrogen (rather than oxygen) on exposure to air, forming a black surface layer of radium nitride (RaN). All isotopes of radium are highly radioactive, with the most stable isotope being radium-226, which has a half-life of 1600 years and decays into radon gas (specifically the isotope radon-222). When radium decays, ionizing radiation is a product, which can excite fluorescent chemicals and cause radioluminescence. - Uranium is a chemical element with symbol U and atomic number92. It is a silvery-white metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weakly radioactive because all its isotopes are unstable (with half-lives of the six naturally known isotopes, uranium-233 to uranium-238, varying between 69 years and 4.5 billion years). The most common isotopes in natural uranium are uranium-238 (which has 146 neutrons and accounts for over 99%) and uranium-235 (which has 143 neutrons). Uranium has the highest atomic weight of the primordially occurring elements. Its density is about 70% higher than that of lead, and slightly lower than that of gold or tungsten. It occurs naturally in low concentrations of a few parts per million in soil, rock and water, and is commercially extracted from uranium-bearing minerals such as uraninite. - The Rioni or Rion River ("Rioni", "Phasis") is the main river of western Georgia. It originates in the Caucasus Mountains, in the region of Racha and flows west to the Black Sea, entering it north of the city of Poti (near ancient Phasis). The city of Kutaisi, once the ancient city of Colchis, lies on its banks. It drains the western Transcaucasus into the Black Sea while its sister, the Kura River, drains the eastern Transcaucasus into the Caspian Sea. - Isotopes are variants of a particular chemical element which differ in neutron number. All isotopes of a given element have the same number of protons in each atom. The term isotope is formed from the Greek roots isos ( "equal") and topos ( "place"), meaning "the same place"; thus, the meaning behind the name is that different isotopes of a single element occupy the same position on the periodic table. - The noble gases make a group of chemical elements with similar properties; under standard conditions, they are all odorless, colorless, monatomic gases with very low chemical reactivity. The six noble gases that occur naturally are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and the radioactive radon (Rn). Oganesson (Og) is predicted to be a noble gas as well, but its chemistry has not yet been investigated. - A chemical element or element is a species of atoms having the same number of protons in their atomic nuclei (i.e. the same atomic number, "Z"). There are 118 elements that have been identified, of which the first 94 occur naturally on Earth with the remaining 24 being synthetic elements. There are 80 elements that have at least one stable isotope and 38 that have exclusively radioactive isotopes, which decay over time into other elements. Iron is the most abundant element (by mass) making up Earth, while oxygen is the most common element in the Earth's crust. - In chemistry, a carbonate is a salt of carbonic acid (HCO), characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C(=O)(O). - Lead, from the Old English "lead", is a chemical element with atomic number82 and symbolPb (after the Latin, "plumbum"). It has the second highest atomic number of all practically stable elements. As such, lead is located at the end of some decay chains of heavier elements, which in part accounts for its relative abundance: its stability exceeds those of other similarly-numbered elements. Lead is a soft, malleable, and heavy metal. Freshly cut lead has a bluish-white color that soon tarnishes to a dull grayish color when exposed to air; as a liquid, it has a shiny chrome-silver luster. Lead's density of 11.34g/cm exceeds those of most common materials. - In nuclear science, the decay chain refers to the radioactive decay of different discrete radioactive decay products as a chained series of transformations. They are also known as "radioactive cascades". Most radioisotopes do not decay directly to a stable state, but rather undergo a series of decays until eventually a stable isotope is reached. - Tsqaltubo ( Georgian : ) is a spa resort in west - central Georgia . It is located at around 42 20 23 '' N 42 35 57 '' E. It is the main town of the Tsqaltubo district of the Imereti province . It is famous for its radon - carbonate mineral springs , whose natural temperature of 33 -- 35 C ( 91 -- 95 F ) enables the water to be used without preliminary heating . The resort 's focus is on balneotherapy for circulatory , nervous , musculo - skeletal , gynaecological and skin diseases , but since the 1970s its repertoire has included '' speleotherapy '' , in which the cool dust - free environment of local caves is said to benefit pulmonary diseases . Tsqaltubo was especially popular in the Soviet era , attracting around 125,000 visitors a year . Bathhouse 9 features a frieze of Stalin , and visitors can see the private pool where he bathed on his visits . Currently the spa receives only some 700 visitors a year , and since 1993 many of the sanatorium complexes have been devoted to housing some 9000 refugees , primarily women and children , displaced from their homes by ethnic conflict in Abkhazia . - An ion is an atom or a molecule in which the total number of electrons is not equal to the total number of protons, giving the atom or molecule a net positive or negative electrical charge. Ions can be created, by either chemical or physical means, via ionization. What entity does 'tsqaltubo' has the relation 'instance of' with?
A:
city