<Tr> <Td> Sulphur dioxide </Td> <Td> (SO) </Td> <Td> trace </Td> <Td> trace </Td> <Td> - </Td> <Td> - </Td> <Td> - </Td> <Td> - </Td> <Td> - </Td> <Td> - </Td> <Td> 1.00 </Td> <Td> (0.0001%) </Td> <Td> - </Td> <Td> - </Td> </Tr> <Tr> <Td> Ozone </Td> <Td> (O) </Td> <Td> 0.02 to 0.07 <P> </P> </Td> <Td> (2 to 7 × 10%) <P> </P> </Td> <Td> - </Td> <Td> - </Td> <Td> - </Td> <Td> - </Td> <Td> 0.01 to 0.10 <P> </P> </Td> <Td> (1 to 10 × 10%) <P> </P> </Td> <Td> 0.02 to 0.07 <P> </P> </Td> <Td> (2 to 7 × 10%) <P> </P> </Td> <Td> - </Td> <Td> - </Td> </Tr> <Tr> <Td> Trace to 30 ppm </Td> <Td> (----) </Td> <Td> - </Td> <Td> - </Td> <Td> - </Td> <Td> - </Td> <Td> 2.9 </Td> <Td> (0.00029%) </Td> <Td> - </Td> <Td> - </Td> <Td> - </Td> <Td> - </Td> <Td> - </Td> <Td> - </Td> </Tr> <Tr> <Td> Dry air total </Td> <Td> (air) </Td> <Td> 1,000,065.265 </Td> <Td> (100.0065265%) </Td> <Td> 999,997.100 </Td> <Td> (99.9997100%) </Td> <Td> 1,000,000.000 </Td> <Td> (100.0000000%) </Td> <Td> 1,000,051.404 </Td> <Td> (100.0051404%) </Td> <Td> 999,998.677 </Td> <Td> (99.9998677%) </Td> <Td> 1,000,080.147 </Td> <Td> (100.0080147%) </Td> </Tr>

At stp the dencity of a gas (molecular weight 45) is