Which of the following statements is/are incorrect? (P) In the vulcanization of rubber, a solution of S₂Cl₂ in CO₂ is used. (Q) Buna-N is copolymer of butadiene and acrylonitrile. (R) Cellulose mononitrate is called commercially as Celluloid, used in photographic films.

(P) Vulcanization is a chemical process for converting natural rubber or related polymers into more durable materials via the addition of sulphur or a solution of S₂Cl₂ in CS₂. (Q) Buna-N is the copolymer of butadiene and acrylonitrile. (R) Cellulose is treated with sulfuric acid and potassium nitrate to give cellulose mononitrate. This was used commercially as Celluloid, a highly flammable plastic used in the first half of the 20^th Century for lacquers and photographic film. Hence, statement P is only incorrect.