I what this question to be solve.what will be the pressure of 50cm^3 of oxygen gas in a piston initially at a pressure of 2atm when the volume was 500cm^3 at a steady temperature of 300k
Recall Boyle's Law:
P1 * V1 = P2 * V2
where
P1 = initial pressure
P2 = final pressure
V1 = inital volume
V2 = final volume
This is applicable if Temperature is held constant. Substitute the given values and solve for P2.
Hope this helps~ :)