What large fissionable nuclei are needed to sustain chain reactions with enough critical mass

At 450 mm hg a gas has a volume of 760 l, what is its volume at standard pressure

Although respiratory organs vary across different organisms, they all contain respiratory surfaces that have a large surface area and are extremely thin. explain why having an extremely thin respiratory surface with a large surface area is advantageous for the process of gas exchange

Identify arrows pointing to bonding electrons. done h-0-0-h ) intro