(a) Define the dipole moment with mathematical expression.
(b) Why is dipole moment of HF higher than that of HCl ?

Explanation

Dipole moment gives a measure of polarity of a molecule. It is defined as the product of charge developed on atom and the distance between the atoms. It is denoted by `mu`.
`mu = q xxd`
(b) F is more electronegative than Cl. Thus, HF has higher dipole moment than HCI.