<prompt> Which of the following is used for room sterilization?FormaldehydeIodineLimeEthylene oxide  <response>: Ans: a Formaldehyde Ref: Park, 19th ed, p. 110For room sterilization disinfectants used are: Chlorine preparations that leave 25 ppm or more chlorine Formaldehyde at 1 or more Phenolic disinfectants e.g., cresol 2.5All these have a contact period of 4 hours before final washing. When fumigation is required gas most commonly used is formaldehyde. The room is kept closed for 6-12 hours to allow disinfection.Ethylene oxide: Heat sensitive articles may be sterilized at 55-60degC by ethylene oxide which kills bacteria, spores tetanus spores and also viruses.Descending order of resistance to sterilization is:PrionsBacterial sporeMycobacteriumNon lipid or small virusesFungiVegetative bacteriaLipid or medium size viruses Most resistant to sterilization is prions AIPGMEE 08. Least resistant to sterilization is lipid or medium size viruses. 