2 out of 13
Which of the following has a net dipole moment of zero?
Ans. D Let us look at the choices one by one. The water molecule is a bent molecule. So there is good reason to believe that it has a net nonzero dipole moment. In HCl, the hydrogen-chlorine bond is a polar bond, and thus there is clearly a separation of charge. This means it has a dipole moment. Oxygen is more electronegative than carbon. This creates a charge separation in the CO molecule. Thus the oxygen has a partial negative charge. So CO is a good candidate, having a net nonzero dipole moment. The CH4 molecule has a tetrahedral structure and the small individual dipoles cancel out. So the net dipole of methane is zero.