Give me the number of valence electrons for so4 2-

1. list three scientific reasons cockroaches may fly.

Can someone me with 3 and 4 plz. this is for masteries test.

When the ionic compound nabr dissolves in water, br– ions are pulled into solution by the attraction between what two particles? a. the na+ and br– ions b. the na+ ion and the negative end of a water molecule c. the br– ion and the positive end of a water molecule d. the br– ion and the negative end of a water molecule