Amount of substance Amount of substance Amount of substance is a standard-defined quantity that measures the size of an ensemble of particles, such as atoms, molecules, electrons, and other particles. It is sometimes referred to as chemical amount. The International System of Units (SI) defines the amount of substance to be proportional to the number of entities present. The SI unit for amount of substance is the mole. It has the unit symbol mol. The proportionality constant is the inverse of the Avogadro constant. The mole is defined as the amount of substance that contains an equal number of elementary entities as there
Khai Si Khai Si Khai Si () is a sub-district ("tambon") in Mueang Bueng Kan District, in Bueng Kan Province, northeastern Thailand. As of 2012, it had a population of 5,294 people. It lies on Highway 212 and the Mekong River and border with Laos, west of Bueng Kan and east of Ho Kham. The sub-district was created in 1979, when nine administrative villages were split from Nong Sawang sub-district (then still named Nong Kheng) to form the new sub-district. The sub-district is divided into 10 administrative villages ("muban"). The sub-district municipality Khai Si is the local government unit responsible for the