The degree of polarity of a covalent compound is measured by the dipole moment ( μ bond ) of the bond defined as:

μ bond = Charge on one of the poles × bond length

μ bond is a vector quantity. The dipole moment of a molecule is the vector addition of all the bond dipole moments present in it. For a triatomic molecule, containing two bond's like H 2 O, μ molecule is given by

μ 2 molecule = μ 2 bond + μ 2 bond + 2 μ bond . μ bond cos θ

θ = bond angle

The % ionic character of a bond is calculated using the equations

% ionic character = 100

= dipole moment when the molecule is assumed to be completely ionic.

(i) Which of the follwing molecule has non-zero dipole moment -