Q.Alkyl halides though polar are immiscible with water.
Step 1. State the polarity fact. Alkyl halides ARE moderately polar (section 10.4.1), because the C-X bond is a polar covalent bond -- so polarity by itself is not what determines water-solubility here.
Step 2. State the missing capability. What water requires for miscibility is the ability to form hydrogen bonds with it, and this needs a hydrogen attached to a strongly electronegative atom like O or N (as in an alcohol's -OH). An alkyl halide has no such hydrogen -- its halogen atom, although electronegative, is not itself bonded to a hydrogen the way an -OH oxygen is, so no O-H...X or similar hydrogen bond can form between an alkyl halide and water.
Step 3. Conclude with the energetic comparison. Because no hydrogen bonding is possible, the intermolecular attraction between two alkyl halide molecules (or between two water molecules, which DO hydrogen-bond strongly with each other) is stronger than any attraction that could form across an alkyl-halide/water interface, so the two liquids remain immiscible (separate layers) despite the alkyl halide's own polarity.
No hydrogen bonding is possible between an alkyl halide and water, so water's own strong hydrogen-bonded network, and the alkyl halide's own van der Waals network, both stay stronger than any cross-attraction between the two, keeping them immiscible.
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