Glucose or sucrose are soluble in water but cyclohexane or benzene (simple six membered ring compounds) are insoluble in water. Explain.

Glucose contains five and and sucrose contains eight –OH groups. These –OH groups from H-bonds with water. Due to this extensive intermolecular H-bonding, glucose and sucrose are soluble in water irrespective of the fact that their molecular masses are 180 g mol–1 and 342 g mol–1 respectively.

In contrast, benzene (molecular mass = 78 g mol–1) and cyclohexane (molecular mass = 84 g mol–1) are simple molecules having low molecular masses. Even then they are insoluble in water. the reason being that these compounds do not contain –OH groups and hence do not from H-bonds with water. 

Alternatively, like dissolves like is the general rule of solubility. Therefore, benzene and cyclohexane which are non-polar molecules do not dissolve in polar water molecules while glucose and sucrose being polar molecules dissolve in polar water molecules.