<P> The first indirect effect is also known as the Twomey effect . Sulfate aerosols can act as cloud condensation nuclei and this leads to greater numbers of smaller droplets of water . Lots of smaller droplets can diffuse light more efficiently than just a few larger droplets . The second indirect effect is the further knock - on effects of having more cloud condensation nuclei . It is proposed that these include the suppression of drizzle, increased cloud height, to facilitate cloud formation at low humidities and longer cloud lifetime . Sulfate may also result in changes in the particle size distribution, which can affect the clouds radiative properties in ways that are not fully understood . Chemical effects such as the dissolution of soluble gases and slightly soluble substances, surface tension depression by organic substances and accommodation coefficient changes are also included in the second indirect effect . </P> <P> The indirect effects probably have a cooling effect, perhaps up to 2 W / m, although the uncertainty is very large . Sulfates are therefore implicated in global dimming . Sulfate is also the major contributor to stratospheric aerosol formed by oxidation of sulfur dioxide injected into the stratosphere by impulsive volcanoes such as the 1991 eruption of Mount Pinatubo in the Philippines . This aerosol exerts a cooling effect on climate during its 1 - 2 year lifetime in the stratosphere . </P> <P> The conjugate base of sulfuric acid (H SO)--a dense, colourless, oily, corrosive liquid--is the hydrogen sulfate ion (HSO), also called the bisulfate ion . Sulfuric acid is classified as a strong acid; in aqueous solutions it ionizes completely to form hydronium ions (H O) and hydrogen sulfate (HSO). In other words, the sulfuric acid behaves as a Brønsted--Lowry acid and is deprotonated . Bisulfate has a molar mass of 97.078 g / mol . It has a valency of 1 . An example of a salt containing the HSO group is sodium bisulfate, NaHSO . In dilute solutions the hydrogen sulfate ions also dissociate, forming more hydronium ions and sulfate ions (SO). The CAS registry number for hydrogen sulfate is 14996 - 02 - 2 . </P> <Table> Sulfur oxyanions <Tr> <Th> Molecular formula </Th> <Th> Name </Th> </Tr> <Tr> <Td> SO </Td> <Td> Peroxomonosulfate </Td> </Tr> <Tr> <Td> SO </Td> <Td> Sulfate </Td> </Tr> <Tr> <Td> SO </Td> <Td> Sulfite </Td> </Tr> <Tr> <Td> O </Td> <Td> Peroxydisulfate </Td> </Tr> <Tr> <Td> O </Td> <Td> Pyrosulfate </Td> </Tr> <Tr> <Td> O </Td> <Td> Dithionate </Td> </Tr> <Tr> <Td> O </Td> <Td> Metabisulfite </Td> </Tr> <Tr> <Td> O </Td> <Td> Dithionite </Td> </Tr> <Tr> <Td> O </Td> <Td> Thiosulfate </Td> </Tr> <Tr> <Td> O </Td> <Td> Trithionate </Td> </Tr> <Tr> <Td> O </Td> <Td> Tetrathionate </Td> </Tr> </Table>

What is the central atom in hso 4 ​ −
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