Solution

To be miscible with water, the solute water force of attraction must be stronger than the solute and water-water forces of attraction. Alkyl halides are polar molecules and so held together by dipole-dipole interactions. Similarly, strong $$H-$$ bonds exist between the water molecules. The new force of attraction between the alkyl halides and water molecules is weaker than the alkyl-halide-alkyl halide and water - water forces of attraction. Hence alkyl halides (though polar) are immiscible with water.