An unknown mass is placed on the piston of a vertical piston-cylinder device containing nitrogen. the piston is weightless and has an area of 1 m2. the outside pressure is 100 kpa and the pressure inside is measured at 101 kpa. determine

(a) the unknown mass.
(b) due to a leak, the piston gradually moves down until the leak is fixed, at which point half the gas (by mass) has escaped. what is the pressure inside in this new position of the piston?
(c) what-if scenario: by what percent will the pressure inside change if the mass placed on the piston is doubled?