OHCH2CH2CH2CH2CH2OH is the most soluble in water.
Explanation:
This molecule has –OH groups at both ends. The –OH will be able to interact positively without water molecules by forming hydrogen bonds with the H ends of water molecules. This is because the –OH ‘s are polar making the molecule also generally polar - which would otherwise be nonpolar without them. Water being a polar solvent it dissolves polar substances.
