lone pairs in compounds

does the presence of a lone pair in a compound always make it polar ?? and why

Generally speaking yes, a lone pair would make a compound polar.
This is because you have a region of space (sub-orbital) that is taken up by 2 electrons. That makes that area of space very negatively charged, we call this an area of high electron density. So if one end of the molecule was very negatively charged and the other end wasn't (i.e. the other end of the molecule doesn't also have a lone pair) there would be a charge difference across the molecule. If this charge difference is big enough we call the molecule a polar molecule.

Hope that helps.

Not necessarily, if the molecule is symmetrical such as carbon dioxide. Each oxygen has two lone pairs but the molecule as a whole is non-polar as the individual dipoles cancel out.

The same is true of sulfur trioxide, but not sulfur dioxide.

so u mean that if there are two lone pairs opposite to each other they cancel out and therefore the molecule becomes nonpolar............. and also in h2o there is onlu one lone pair so it makes it polar right??

one more thing.. what is meant by a lone pair is directional
thank u very much xx