s  

In chlorobenzene, the Cl-atom is linked to a sp${}^2$ hybridized carbon atom. In cyclohexyl
chloride, the Cl-atom is linked to a sp${}^3$ hybridized carbon atom. Now, sp${}^2$ hybridized carbon
has more s-character than sp${}^3$ hybridized carbon atom. Therefore, the former is more
electronegative than the latter. Therefore, the density of electrons of C−Cl bond near the
Cl-atom is less in chlorobenzene than in cydohexyl chloride.
Moreover, the −R effect of the benzene ring of chlorobenzene decreases the electron
density of the C−Cl bond near the Cl-atom. As a result, the polarity of the C−Cl bond in
chlorobenzene decreases. Hence, the dipole moment of chlorobenzene is lower than that
of cyclohexyl chloride.
(ii) To be miscible with water, the solute-water force of attraction must be stronger
than the solute-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.

(iii) Grignard reagents are very reactive. In the presence of moisture, they react to give
alkanes.

$\stackrel{\varsigma -}{R} \stackrel{\varsigma +}{M}R \stackrel{\varsigma -}{X}+ H_{2}O\to R-Hj+ Mg \left(OH\right) X$
$Grigrad Alkane$
$regent$

AnTherefore, Grignard reagents should be prepared under anhydrous conditions.