If all the reactors are used, the pressure inside the flask will most likely increase to 4 atm.
Atmospheric pressure is a force per unit area exerted by the air in the atmosphere on the Earth's surface. The value of atmospheric pressure above sea level is 1013.25 hPa.
The atmospheric pressure varies from different meteorological factors such as:
According to the above, if all the reactors are used at atmospheric pressure, it will most likely increase.
Note: This question is incomplete because some information is missing. However I can answer it based on my prior knowledge.
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