You are a new engineer at crud chemical and you want to make sure things are safe! a 1000- gallon vessel that is filled with atmospheric air at 760 mmhg and 20°c is to be inerted by siphon purging. on each cycle, 600 gallons of water are used to fill the vessel and are replaced with purge gas as the vessel is drained. benzene (c6h6) is to be charged to the vessel when the atmosphere is inert. a) what is the minimum oxygen concentration for benzene? [5 points] b) how many siphon-purge cycles with pure nitrogen are needed to create an atmosphere that has a 4% margin of safety? (ie. the final oxygen concentration is 4% below the moc) [10 points] atmospherethalhas a 4% margin one cycle if the purge gas contains 1% oxygen?