In a number of combustion systems, almost pure oxygen is fed for combustion even though nitrogen can be assumed to be mostly inert. oxygen is produced via cryogenic separation of air and this process is very expensive. cite at least two reasons why you think oxygen is separated from air for these combustion systems

Ans. : frostbite is when exposure to cold temperatures causes freezing to the skin or other tissues. it most commonly affects the hands, feet, and face. the longer areas are exposed to cold, typically the worse the frostbite. the water temperature used for rewarming a frostbitten part should be : (102 -105) f degrees.

B) movement of materials into and out of the cell