Order of Solubility of given alcohols is as follow,
Ethanol Butanol Hexanol
Highly Soluble ---------->--------------------->------------------------>---Slightly Soluble
As we know Like dissolves Like. Water is a polar solvent and dissolves readily those compounds which are polar in nature. The solubility of all these alcohols is due o the -OH (hydroxyl) group which tends to form Hydrogen Bond interactions with the water molecules. The difference comes in the alkyl group of these compounds. The akyl group is non polar in nature and immiscible in water. As the non polar chain increases from ethanol to hexanol, so the solubility also decreases from ethanol to hexanol.
