The volume of a gas is 0.40 l when the pressure is 1.00 atm. at the same temperature, what is the pressure when the volume of the gas is 2.0 l

             P₂  =  0.2 L

Solution:
              Lets suppose the gas is acting ideally, then according to Boyle's law, "The volume of a fixed mass of gas at constant temperature is inversely proportional to the applied pressure". Mathematically for initial and final states the relation is as follow,

                                                 P₁ V₁  =  P₂ V₂

Data Given;
                   V₁  =  0.4 L

                   P₁  =  1 atm

                   V₂  =  2 L

                   P₂  =  ??

Solving equation for P₂,

                          P₂  =  P₁ V₁ / V₂

Putting values,

                          P₂  =  (1 atm × 0.4 L) ÷ 2 L

                          P₂  =  0.2 L

Result:
            As the volume has been increased, therefore, the pressure is decreased from 1 atm to 0.2 atm.