Why are alkanes insoluble in water but soluble in organic solvents?A) they have high densityB) they have weak bondsC) they cannot break the bonds in waterD) all of above

The correct answer is C) they cannot break the bonds in water.

Alkanes are non-polar molecules, meaning they lack charged poles. Water, on the other hand, is a highly polar molecule due to its asymmetrical distribution of charge (the oxygen atom is more electronegative than the hydrogen atoms, creating a partial negative charge on the oxygen and partial positive charges on the hydrogens).

Since "like dissolves like", non-polar molecules like alkanes tend to be insoluble in polar solvents like water. The reason for this is that water molecules are strongly attracted to each other through hydrogen bonding, and these attractions are much stronger than the relatively weak London dispersion forces that hold alkanes together. Hence, water molecules would rather stick to each other than to non-polar alkanes, resulting in poor solubility.

However, alkanes are soluble in other non-polar or weakly polar organic solvents because these solvents can overcome the weak intermolecular forces present in alkanes, allowing them to dissolve. Therefore, the key factor is the inability of water to disrupt the intermolecular forces holding alkanes together.