hexane is a carbon chain of 6 carbon atoms. aliphatic means that there is no double or triple bonds, only single bonds between the carbon atoms. like this:
Hexane is a hydrocarbon with the chemical formula C6H14. n-hexane is the unbranched isomer of hexane as there exists four more branched isomers of hexane
hexane and octane is easier to separate than hexane and heptane because the difference in their boiling points is greater thus hexane will distill out of solution more completely before octane
Hexane is an important non-polar solvent. This means it is extremely useful in dissolving non-polar compounds. It also has a high volatility, so it evaporates relatively quickly.