(a) Why are alkyl halides insoluble in water?

(b) Why is Butan-1-ol optically inactive but Butan-2-ol is optically active?

(c) Although chlorine is an electron withdrawing group, yet it is ortho- , para- directing in electrophilic aromatic substitution reactions. Why?

(a) Alkyl halides are insoluble in water because of their inability to form hydrogen bonds.

Explanation: H-bonds are formed when hydrogen is bonded with highly electronegative atom like F, O or N. In alkyl halides hydrogen is bonded only to carbon which is very less electronegative.

(b)

In butan-2-ol the second carbon is an asymmetric one i.e., the carbon is attached to four different groups. For a compound to be optically active there must be asymmetric carbon present. Hence, butan-2-ol is optically active whereas butan-1-ol is not.

(c) Chlorine is an electron withdrawing group, yet it is ortho- , para- directing in electrophilic aromatic substitution reactions because during resonance the electron density is found at ortho- and para- positions only.