<Tr> <Td> Water </Td> <Td> </Td> </Tr> <Tr> <Td> Table salt </Td> <Td> 2.17 </Td> </Tr> <Tr> <Td> Aluminium </Td> <Td> 2.7 </Td> </Tr> <Tr> <Td> Cement </Td> <Td> 3.15 </Td> </Tr>

4. if pure water has a specific gravity of 1 why is the specific gravity of urine higher