<prompt> PIN number of oxygen is2,53,52,63,6  <response>: Ans: a 2,5 Ref: Ajay Yadov, 2nded, p. 22Pin index for gasesOxygen-2,5 Entonox5002 50N2O-7Nitrous oxide-3,5 Carbondioxide7.5-2,6Cyclopropane-3,6 Carbondioxide 7.5-1,6Air-1,5 Nitrogen-1,4 