In which of the following compounds does Cl have the most positive partial charge? The problem is :

In which of the following compounds does Cl have the most positive partial charge?

SCl2 ,, HCl  ,, BrCl  ,, OCl2 ,,  

before I go through how I will solve this problem .. There is a question : Can Cl have a partial positive charge?

Well, all of them are polar, so there is a partial charge on each one of them

but how to compare or specify the partial charges?

The only thing I can think about is electronegativity

is it like .. the greater the difference in electronegativity the more the partial charges ?

Or .. ?
The greater the difference in electronegativity the more the partial charges is true. Compare the electronegativities of the atoms bonded with chlorine and you can easily determine in which compound chlorine has the biggest partial charge. Chlorine can have a partial positive charge when it's bonded with a more electronegative element like oxygen or fluorine.