for state of nj only. can a gas station charge a different price per gallon of gas for cash or charge card.?

Yes, they can. Most gas stations now have the same price for either, but in order to accept credit cards, they have to get special equipment that can read the cards. Also, they are charged a fee for each card they accept. Larger gas stations can do this because they get the volume this way, while "Mom & Pop" gas station have a limited ceiling and don't necessarily get the volume (as in on the highways).

I hope this helps.

Yes. It costs them more to process a credit card payment, so the station makes less profit. I don't like it and won't usually buy gas from stations that do that because I seldom carry cash.