He’s got at least 2 missiles, maybe 4, but definitely no tanks under the wings.
Does the J10 have that sort of range on internal fuel plus maybe one centerline tank? Or did they top up with a tanker and/or are flying out of one of the island bases?
J-10 is capable of mid-air refueling so it is entirely possible for it to operate so far out on the South China sea. I don't think it landed on any of the islands since we heard no fuss from the media about it (like when J-11s did land).