Explain why sulfur dioxide and acetic acid have dipole moments. Use an electronegativity argument. Solution * Sulphur dioxide has bent shape with one lone pair on Sulphur and two oxygen atoms are more electronegative than Sulphur. Hence the bond pair of electrons are strongly attracted by oxygen atoms where as lone pair move in opposite direction and net there exists some unequal distribution of electrons around central sulphur. Thus sulphur dioxide exhibits dipole moment. ** In Acetic acid the central C is attached to one - CH 3 group, one O with double bond and one - OH gorup. Around this Carbon, the shape is trigonal plananr. Since the electronegativity of O is greater than C, the bond pair of electrons spends more time nearer the O and hence there exists unequal distribution of electrons around central C. Thus the molecules has a net dipole moment. .