Question

The dipole moment of phenol is smaller than that of methanol. Why?

Answer 1

In phenol carbon is $s{p}^2$ hybridized and due to this reason benzene ring is producing electron withdrawing effect.
On the other hand, carbon of methanol is $s{p}^3$ hybridized and produces electron releasing effect (+ effect) Thus. C - O bond in phenol is less polar than C - O bond in methanol and therefore, the dipole moment of phenol (1.54 D) is smaller than that of methanol (1.71 D).