<Table> Aqua regia <Tr> <Td_colspan="2"> </Td> </Tr> <Tr> <Th_colspan="2"> Names </Th> </Tr> <Tr> <Td_colspan="2"> IUPAC name nitric acid hydrochloride </Td> </Tr> <Tr> <Td_colspan="2"> Other names aqua regis, nitrohydrochloric acid </Td> </Tr> <Tr> <Th_colspan="2"> Identifiers </Th> </Tr> <Tr> <Td> CAS Number </Td> <Td> <Ul> <Li> 8007 - 56 - 5 </Li> </Ul> </Td> </Tr> <Tr> <Td> 3D model (JSmol) </Td> <Td> <Ul> <Li> Interactive image </Li> </Ul> </Td> </Tr> <Tr> <Td> PubChem CID </Td> <Td> <Ul> <Li> 62687 </Li> </Ul> </Td> </Tr> <Tr> <Td_colspan="2"> SMILES (show) <Ul> <Li> (N+) (= O) (O) (O -). Cl </Li> </Ul> </Td> </Tr> <Tr> <Th_colspan="2"> Properties </Th> </Tr> <Tr> <Td> Chemical formula </Td> <Td> HNO + 3 HCl </Td> </Tr> <Tr> <Td> Appearance </Td> <Td> red, yellow or gold fuming liquid </Td> </Tr> <Tr> <Td> Density </Td> <Td> 1.01--1.21 g / cm </Td> </Tr> <Tr> <Td> Melting point </Td> <Td> − 42 ° C (− 44 ° F; 231 K) </Td> </Tr> <Tr> <Td> Boiling point </Td> <Td> 108 ° C (226 ° F; 381 K) </Td> </Tr> <Tr> <Td> Solubility in water </Td> <Td> miscible in water </Td> </Tr> <Tr> <Td> Vapor pressure </Td> <Td> 21 mbar </Td> </Tr> <Tr> <Th_colspan="2"> Hazards </Th> </Tr> <Tr> <Td> NFPA 704 </Td> <Td> 0 0 OX </Td> </Tr> <Tr> <Td_colspan="2"> Except where otherwise noted, data are given for materials in their standard state (at 25 ° C (77 ° F), 100 kPa). </Td> </Tr> <Tr> <Td_colspan="2"> Infobox references </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> </Tr> </Table> <Tr> <Th_colspan="2"> Names </Th> </Tr>

What is the chemical formula for aqua regia
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