Agas initally has a volume of 25 l at a pressure of 90 kpa. if the gas is allowed to expand to 50 l. what is the final pressure?

Since the change occurs at constant temperature (i.e. an isothermal change), boyle's law applies,i.e. p1v1 = p 2 v 2 where p1 = 150 kpa, p 2 = 750 kpa and v1= 1.5 m3
hence, (150)(1.5) = (750)v 2from which, volume v 2 =150 1.5750  = 0.3 m

You use the atomic number to find out how many protons and neutrons there are in the atom. you use the atomic mass to find out how many protons and electrons there are in the atom.