[mol]

 I couldnt understand on how to draw a vector symbol, or 0  in the dipole moment diagram. say eg CCl4 or anything.. does it have a rule up / down arrow or horizontal or 0 and  to which direction it points? pls help
thanks

[Schrödinger]

There is no rule. It depends on how you draw the molecule on paper.

If dipole moment is zero (as is the case with CCl4), then there is no arrow. You just say that it has zero dipole moment.