<Tr> <Th> IUPAC name </Th> <Td> butane </Td> <Td> 2 - methylpropane </Td> </Tr> <Tr> <Th> Molecular form </Th> <Td> </Td> <Td> </Td> </Tr> <Tr> <Th> Boiling point (° C) </Th> <Td> − 0.5 </Td> <Td> − 11.7 </Td> </Tr> <Table> Comparison of pentane isomer boiling points <Tr> <Th> Common name </Th> <Td> n - pentane </Td> <Td> isopentane </Td> <Td> neopentane </Td> </Tr> <Tr> <Th> IUPAC name </Th> <Td> pentane </Td> <Td> 2 - methylbutane </Td> <Td> 2, 2 - dimethylpropane </Td> </Tr> <Tr> <Th> Molecular form </Th> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Th> Boiling point (° C) </Th> <Td> 36.0 </Td> <Td> 27.7 </Td> <Td> 9.5 </Td> </Tr> </Table>

How does external pressure affect the boiling point