<P> Manganese is part of the iron group of elements, which are thought to be synthesized in large stars shortly before the supernova explosion . Mn decays to Cr with a half - life of 3.7 million years . Because of its relatively short half - life, Mn is relatively rare, produced by cosmic rays impact on iron . Manganese isotopic contents are typically combined with chromium isotopic contents and have found application in isotope geology and radiometric dating . Mn--Cr isotopic ratios reinforce the evidence from Al and Pd for the early history of the solar system . Variations in Cr / Cr and Mn / Cr ratios from several meteorites suggest an initial Mn / Mn ratio, which indicates that Mn--Cr isotopic composition must result from in situ decay of Mn in differentiated planetary bodies . Hence, Mn provides additional evidence for nucleosynthetic processes immediately before coalescence of the solar system . </P> <P> The most common oxidation states of manganese are + 2, + 3, + 4, + 6, and + 7, though all oxidation states from − 3 to + 7 have been observed . Mn often competes with Mg in biological systems . Manganese compounds where manganese is in oxidation state + 7, which are mostly restricted to the unstable oxide Mn O, compounds of the intensely purple permanganate anion MnO, and a few oxyhalides (MnO F and MnO Cl), are powerful oxidizing agents . Compounds with oxidation states + 5 (blue) and + 6 (green) are strong oxidizing agents and are vulnerable to disproportionation . </P> <P> The most stable oxidation state for manganese is + 2, which has a pale pink color, and many manganese (II) compounds are known, such as manganese (II) sulfate (MnSO) and manganese (II) chloride (MnCl). This oxidation state is also seen in the mineral rhodochrosite (manganese (II) carbonate). Manganese (II) most commonly exists with a high spin, S = 5 / 2 ground state because of the high pairing energy for manganese (II). However, there are a few examples of low - spin, S = 1 / 2 manganese (II). There are no spin - allowed d--d transitions in manganese (II), explaining why manganese (II) compounds are typically pale to colorless . </P> <Table> <Tr> <Th_colspan="2"> Oxidation states of manganese </Th> </Tr> <Tr> <Td> 0 </Td> <Td> Mn (CO) </Td> </Tr> <Tr> <Td> + 1 </Td> <Td> MnC CH (CO) </Td> </Tr> <Tr> <Td> + 2 </Td> <Td> MnCl, MnCO, MnO </Td> </Tr> <Tr> <Td> + 3 </Td> <Td> MnF, Mn (OAc), Mn O </Td> </Tr> <Tr> <Td> + 4 </Td> <Td> MnO </Td> </Tr> <Tr> <Td> + 5 </Td> <Td> MnO </Td> </Tr> <Tr> <Td> + 6 </Td> <Td> MnO </Td> </Tr> <Tr> <Td> + 7 </Td> <Td> KMnO, Mn O </Td> </Tr> <Tr> <Td_colspan="2"> Common oxidation states are in bold . </Td> </Tr> </Table>

What is the oxidation number of manganese in the mn ion