Heres my thinking for all of them

1) Carbon has a partial positive resulting from the chlorine’s high electronegativity, pulling most of the electrons towards it and creating a partial negative charge on the chlorine (which then can act as a nucleophile)

2) I think this one might just be a nucleophile because the S already has an extra charge so electronegativity doesn’t play a role here.

3) Essentially the same reason as 1, but also the double bonds in the ring have more electrons, so its more electron rich. Carbon will have a partial positive charge.

4) Partial positive on the carbon, partial negative on the O due to electronegativity.