a. Positive electrode (anode) half-reaction:
2H2O(l) → O2(g) + 4H^+(aq) + 4e^-
The gas being produced at the positive electrode is oxygen (O2(g)).
b. Negative electrode (cathode) half-reaction:
2H^+(aq) + 2e^- → H2(g)
The gas being produced at the negative electrode is hydrogen (H2(g)).
Overall reaction:
2H2O(l) → 2H2(g) + O2(g)